Wow! There are lots of high spec computers!
Here is mine.
CPU:Core 2 Duo E6600 Non-overclocked.
RAM:PC4200 DDR2 SDRAM 1GB
HDD: Samsung SATA2 200GB(I'm regretting it)
Graphic card:Geforce 7600GS 256MB
Motherboard:GA-965P-DS3
and a DVD-Multi drive and a FDD.

My PCs Specs:

Laptop:
-Dell Vostro 1700
-CPU: Intel(R) Core(TM)2 Duo T8300 / 2,4 GHz per core
-RAM: 4 GB
-Graphic-card: NVIDIA Geforce 8600M GT
-OS: Windows Vista Ultimate // Ubuntu Hardy Heron 8.04
-HDD1: FUJITSU MHW2160BJ FFS G2 // 160 GB
-HDD2: Hitachi HTS722016K9A300
-Wireless-Card: Intel(R) Wireless WiFi Link 4965AGN

Desktop.
-Vendor: Medion
-CPU: Intel(R) Celeron(R) / 3,06 GHz
-RAM: 2 GB
-Graphic-card: A integrated one
-OS: Windows XP Home Edition SP3
-HDD1: Seagate ST318081

CPU: Intel Core2 Quad Core Q6600 @ 2.40ghz
RAM: 4GB
MOTHERBOARD: ASUS P5N-E SLI
OS: Windows XP Pro
Hard Drives:
1x80gb IDE
2x500gb SATA
DVD-RAM Drive
Bluetooth
GPU: Geforce 7900 GS 256mbs
hp pavilion mx70
realtek RTL 8185 wireless LAN network adapter
Genius speakers

4gigs RAM and no x64 os?
Then you should have 3.5gigs at most.

Why not upgrade to an x64 OS then you can use all your memory and even upgrade.

yep i got 4GBs of ram and its XP Pro x86 its a boot.ini hack give me 2 mins i show you it

Antec 900 Case
Intel Core 2 Quad Q6600 @3GHz
OCZ Vendetta
Gigabyte GAEP45-DS3L
Palit 4850 Sonic
4GB OCZ Platinum 800MHz
WD 640GB HDD
Samsung 320GB HDD
Corsair 550Watt PSU
Asus TV Tuner
LG 22X DVD RW Drive
Vista Ultimate SP1 X64

Updated: (Not the best, but better then my old PIII 700 Toshiba from before)
Pentium 4 2.8GHz (2.96GHz OC)
512MB Ram (Got another 512 stick on the way)
80GB Sata HDD
80GB IDE HDD
160GB External HDD
Asus DVD-Burner
Asus CD-Writer
128MB Onboard SiS Graphics (Hello BIOS Hack, but have a AGP Card also on the way)
Asus 19" Widescreen HD LCD
Windows XP Home SP3 (I was going to format and stick Pro back on, couldn't be bothered with the SATA Drivers Pre-install)

Eheheh, Firefox doesn't cry anymore when I want to watch a Flash Vid

My Specs
AMD Athlon 64x2 4200 OCED to 150%
ATI HD2400XT OCED TO 180%
4 GB OCZ GOLD GAMING RAM (Oced like processor)
240GB WD CAVIAR, 40 GB WD Protoge
DVD UBERDRIVE!!!
550W CoolerMaster EXTREME POWER psu
VISTA ULTIMATE x86 (i had 64 bit, but I couldnt use many of my games) (W7 ASAP!)
2x 19" westinghouse Flatpanels using dvi
El-Cheapo Wireless card
Gigabit onboard Lan
Onboard Audio
cigarette lighter
sega genesis cart slot
Playstation controller port
(NO FIREWIRE) (Yet)

EDITED BECAUSE CLASS GOT OVER

Here's my spec...

Intel Core 2 Quad Q6600 @ 3.42 Ghz
Patriot 4GiB DDRII 800
MSI SLI V2 Motherboard
XFX Fatality 8800GTS
250GB + 160GB Sata II HDD
Linux Mint + Windows Vista x64
22" Flatron Wide Display

Intel(R) Celeron(R) CPU 2.66GHz
1022MB RAM
102 GB Total
RADEON 9600 SERIES

I fail

HP compaq 8730w
intel core 2 duo t7300
3 gb ram 667
nvidia quadro 1600m
17 in - 1680x1050

I've got:
Core2 Quad Q6600 @ 3.6 GHz (the processor can handle 3.7 w/ more volts)
DFI LP LT X38-T2R
nVidia 9800GTX @ 825/2030/1235
4GB G. Skill @ 500MHz, 5-5-5-15
2x500GB WD5000AAKS (Raid 0)
SoundBlaster X-Fi Fatal1ty Pro
Lian-Li PC-G75B

I think that's all the important stuff.

Acer Aspire One
1.6ghz Atom
1.5GB Ram
40GB 1.8" Zif Drive
Vista Ultimate x32
Runs Smooth

well i have a whopping 386mb ram on a 1.988 ghz 64 bit cpu take that *sarcasm*

i also have a 2.8 ghz dual core 4gb ram 64 bit vista ultimate with a 500 gb hard drive

AMD 4400+ X2 S939 OCd
2gb Corsair XMS DDR
4TB of HDD
NZXT. Zero Case
1200W NZXT. PSU
ATI x850XT Crossfired.

Intel Core2Quad Q9550 2.83ghz
Thermaltake 760i BigWater Cooling
eVGA 780i SLI A1 Motherboard
Corsair Dominator DDR2 1066 5-5-5-15 with cooling fan
2x XFX GTX280 ( one stock and one xtreme edition)
clocks (602,1107,1296 mhz) XT clocks (640 mhz,1200 mhz, 1404 mhz)
Thermaltake Armour+
Corsair HX1000W Power Supply

Intel C2D E8400 @ 3.0Ghz
2*1 Gig Transcend DDR2 800Mhz
Nvidia 8400GS (For COD4, and not Crysis)
500GB HDD
And, Windows XP

My specs (i have many more computers but then the thread would be very long so here are the computers i use everyday)

Desktop

Intel Core 2 Duo E6400 2.2Ghz (I'm gonna spend my Christmas money on a Quad Core)
4GB DDR2 800MHz Ram (Crap 'Ol 32-Bit windows sees only 3.2
Twin Seagate SATA 250Gb HDDs
Palit NVIDIA 9500GT Video Card
Windows Vista Ultimate RTM (Almost never use)
Windows XP Media Center Edition SP3
iCute Case with Blue LED Fans and a annoyingly intense blue power light

Laptop #1
AMD 1.8Ghz Dual Core (64Bit)
120GB HDD
2GB Ram
Windows Vista Ultimate and Windows 7 6780

Laptop #2
1.2Ghz Pentium III M
512MB Ram
40GB HDD
Windows .Net Server build 3531 with the timebomb set to expire in 2016

Thermaltake V1000 Case
Asus P5K SE Motherboard
Intel Core 2 Quad Q6600 8Mb Cache G0 Rev.
2x2GB RAM DDR1200 (can't remember brand, sorry)
3x WD 500GB SATA Drives
eVGA 8800 GTS 320MB
LG DVD-RW GSA-H20N
LG L204WS 20" LCD
Logitech Keyboard, Microsoft Mouse and Logitech Z-220 Speakers
Running Dualboot between Vista SP1 & OSx86 10.5.5 (iDeneb)

I also own a B&W G3 350 which is running Tiger 10.4.11 atm.

Computer 1 :
CPU : AMD 64 3000- 1.8Ghz(OC'ed to 2.03Ghz)
Ram : 512 MB DDR1-333(Dual-Channel)
HDD0 : 40GB | HDD1 : 20 GB
GFX : Nvidia Geforce 6800 GT
PSU : 400 Watt
OS : Whistler 2008 (Windows XP SP3 heavy modified)

Computer 2:
CPU : Intel Pentuim 4 Extreme (with HT) 3.60 Ghz (OC'ed to 4.2 Ghz)
Ram : 2GB DDR2-800Mhz (Dual-channel)
HDD : 500GB SATA2
GFX : Nividia Geforce 7500
PSU : 550 Watt
OS : Whistler 2008 (Windows XP SP3 heavy modified)

Laptop 1 (Main):
Brand :: HP Compaq nx9010
CPU : 2.8 Ghz
Ram : 512MB ram DDR1-333Mhz(single-channel)
HDD : 40GB
GFX : ATI Mobility 345 64MB(shared)
OS : Whistler 2008 (Windows XP SP3 heavy modified)

Laptop 2 (fileserver) :
Brand :: Xodd
CPU : 2.0 Ghz
Ram : 512MB ram DDR1-333Mhz(single-channel)
HDD0 : 40GB | External HDD1 : 500GB
GFX : SIS 8MB(shared)
OS : Whistler 2008 (Windows XP SP3 heavy modified)

TabletPC :
Brand : Fujitsu Stylistic 3500
CPU : 500Mhz
Ram : 256MB SD-Ram
HDD : 80GB
GFX : ATI (something) 4MB(non-shared)
OS : Windows 2000 SP4

well that was my list.

My PC is inferior to some of these amazing systems, but it does all I need it to, and I have yet to find a game it doesn't run on highest:

3GB DDR2 RAM,
2.6GHz AMD 64 X2,
160GB Internal + 500GB Iomega External,
Zotac Geforce 8800GT 512MB DDR3,
20" Samsung SyncMaster 2032,
Labtec 2.1 Speakers,
650W Power Supply,
DVD/RW

CPU: AMD Athlon 64 3500+
RAM: 3GB
GPU: nVidia GeForce 6600
HD: 2x80GB
Motherboard: Asus A8V-Deluxe
480W power supply
17" BenQ monitor..

CPU: Pentium Dual Core e5200@3,2Ghz
Motherboard: MSI P35 Neo-F
RAM: A-Data Extreme Edition 4GB Cl4
GPU: GeForce 9800GT
HDD: Samsung F1 160GB
Chieftec 450W power supply

SPECS:

CPU: Intel Core 2 Duo E4600 @ 2.40 GHz
RAM: 1x2 GB Corsair XMS2 DDR2 PC-6400 (800MHz)
Video Card: nVidia 8600 GT 256 MB
HDD: 2x500 GB
Monitor: IBM L180P 18.4" ThinkVision

I don't I if shall say SHOW OFF ..or HIDE OFF my specs.. but here it goes
Intel P4 1.6 Ghz
Intel 845WN Motherboard
768 MB SD RAM
120 GB HDD
22 inch Acer LCD
Microsoft 3000 Mouse