Windows XP Problems

My Configuration:

BIOSTAR GF8200 M2+
AMD Athlon64 X2 5000+ 2.6 GHz
2x1GB DDR2-667 Transcend
ASUS HD3650 256MB GDDR3
WD Caviar 250GB SATAII
....

My problem is next: when I installed Windows XP SP3 slipstreamed on Windows XP SP2 bootable CD, I couldn't start Windows after the installation, it fell in a non-stop restart loop. So, I installed Windows XP SP2, then a AMD processor fix, and then Windows XP SP3. It worked fine, untill I started to install drivers and programs. When I finished installing drivers and programs, Windows started to do sh**! It took him very long time to install any other program, when I want to open My Computer, i takes him up to 5 seconds to open the window, and about the same time to close any open window. Before this installation of XP, I had installed Windows Vista, and it worked perfectly. When I gave up Windows XP, I installed Windows Vista again, installed all of the programs, drivers, SP1, fully updated system. Computer worked absolutly perfect, and 2 months after that, I decided to reinstall windows, I made a slipstream of Windows Vista SP1. I installed it, and it started to do the same sh** as XP did! I didn't belived it! I started thinking, and since this motherboard has nVidia chipset, and my graphics card is ATi, i thought that there is some kind of conflict betveen those two components.When I bought this graphics card, I already had ASUS EN7300GT on the same configuration with Win XP installed and it worked fine. Then I bought this card, putted it in the computer instead of 7300GT, deleted the nVidia drivers for graphics, installed ATi drivers, and it worked fine. Other solution might be in slipstream, since it happend only with slipstreamed installations. I don't want to reinstall windows again utill I hear your advices!

Thank you!

I'll try, that's for sure! I use Vista for now 4 months, every game i tried (except GTA IV) worked perfectly on high details, thats the most important thing for me. I'll just complete GTA tomorrow so that I don't have to "expose my computer to wrath of GTA" I'll just try with XP because I have 2 GB of RAM, when I put 2 more, i'll install Vista, because Vista uses all 4GB of RAM.