@supra107 are you on 64 or 32 Bit system?
If you are on 64 bit you don't need to uninstall VPC 2007 at all
1. Install Windows Virtual PC
PS: If you install Virtual PC 2007 don't install it into Microsoft Virtual PC 2007 folder
2. delete this key from registry: [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\899384DAA9E2504438FF E6 05A34FC9BB]
PS: Your key name will be maybe difrent so to check which it is just go to: [HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products and search for "PC 2007"
3. Now download:
http://nookkin.com/download/VPC2007Workaround.zip
4. rename Virtual PC.exe to Virtual PC.bin and copy Virtual PC.exe to the install folder
PS: It's good to have this fix because it will check if Windows Virtual PC and Virtual PC 2007 are opened in the same time
5. Open the vpc-license.reg file with Notepad. On the last line of the file, replace the string "AAAAA-BBB-CCCCCCC-DDDDD" with your Windows product ID, which can be found by right-clicking My Computer and clicking Properties. Then, save the file and double-click on it to add the information to the registry. Be sure to enter your real product ID before double-clicking on the file!
6. double-click on vpc-shell.reg to add shell associations to the registry
Hope it helps