Hey,
i want to build a costum Version of windows like the others. I don't want to do this now but i have some questions.
Do i have to hack the Setup? Or is there a programm which converts the installed Windows into a install-CD? (like remaster(linux)?).
How can i costumize the style of the setup (the beground for example)?
Which programm is the best, Reshacker?

Just install Windows. Then do whatever you want, customize, whatever, than copy everything in C: to the install.WIM and viola!!!

"nlite" and "setup studio" for custom os settings and applications
but for the rest i dont know

This is a really great resource. Saved my life many times.

Or, if it's XP or before, I think you can repack the .xx_ files, they are normal CABs, but I think signatures will stop you.