It doesn't hurt to test...
I was upset also because I RMA my 5800 ultra a few weeks ago because my system all of a sudden showed me a large bar code of colors on the screen during post and in Windows, I could tell I was in Windows because I could hear the sound when entering and it worked fine from March until then.
Then I bought the 5600 Ultra and had same exact problem...
So I RMA my mobo which was a 1.0 board and purchased a new 2.0 board.
After both of those new purchases and RMA's I still had same problem...
Last thing was to get a new power supply I threw out my 350 watt and bought a 600 watt and everything is fine now.
I also re-formatted my system and re-installed everything and that's when I went to play BF with my new video card to see how it played and that's when I noticed all the stuttering and I mean real bad I couldn't play, it looked as if it were lag, but I wasn't playing online I tested while playing single player...
I remembered that I had same problem back when my 5800 Ultra was in and my system was new back in March of this year.
It was the SYSTEM RESTORE feature in Windows XP...
I'm sorry if it doesn't work for everyone but it worked both times for me like a charm...
You can also turn off INDEXING on the drives also, but you must do a defrag once you disable these, because it opens up space and fragments the hell out of the drive.
(2) Asus A7N8X Deluxe 1.0 and 2.0 Boards
Geforce FX 5800 Ultra and 5600 Ultra
AMD Athlon XP 2700+
1.5 Gig Corsair XMS RAM Dual Channel
(2) Plextor CDRW Drives
(2) 80 Gig Seagate SATA Hard Drives