I've already installed SP2 quite a long time ago, but I'll describe the situation a bit more detailed:
so when i open a program, such as Word, but also UT2004, I first get a dialog that's titled "Microsoft Office Professional edition 2003". After it gathers the required info and configures office, a new dialog box is generates, which is titled "Windows File Protection" and says "Windows files must be installed for your installation to proceed. Insert your windows XP Home edition Service Pack 2 CD now."
I guess they are forcing me somehow to either buy another CD of XP (which I find a rip-off), format my hard disk (I prefer not to, because it would take a lot of time...) or hack my way around this issue.
Anyway, tnx for previous reply! I really appreciate your help.