
Well WinXP is superior to Win2000, in fact the marketing blurb and a few fancy bells and whistles aside, WinXP is essentially Win2000 with a newer service pack. Win98SE should still do you proud though, I would point my finger at some wierd compression algorithm used by ATI which is causing your problem. Some facts to consider, are you o/c'ing anything, if so set them back to defaults as encoding will really stress your system, still unlikely if it happens so quickly after encoding. I take it you can run multiple loops of 3Dmark2001SE and other stressful 3D games or burn-in progs, if they all run without a glitch that should rule out hw probs. Trying a few different progs would rule out a rpob with a particular prog so that would only leave some wierd rthing with Windows itself. I do know that Windows98 was never designed to manage more than 256MB of RAM, this could be causing you some wierd fproblems and if you have 2 DIMMs in there try taking one of them out. Another thing to try is entering BIOS and setting the RAM timings (latency etc) to the higher (and therefore slower) settings, the perf diff is pretty minimal, as usual with alteration of BIOS settings keep a strict log of what you change from and to so you can change things back if they don't help.

As a final note, what gfx card are you using? You say GF MX,if you have any gaming aspirations whatsoever then you really should consider a GF3TI200 or Rad8500LE as a minimum, they are under $100 and miles better than any GF MX card, even the GF4MX460 (marginally faster than a GF2TI). That XP2200+ will be almost entirely wasted for gaming otherwise, a GF4TI4200-128MB should be a consideration, they o/c to either 4400 or 4600 speeds and are great all-rounders and fantastic value. Of course gaming for some is a of secondary importance (or less) and if this is the case for you, don't worry. Just bear in mind that an XP2200+ & GF4MX will perf worse for gaming than an XP1600+ & GF4TI.