I am not a newbie to Microslop's op systems. I was just sharing an experience, hoping for an answer. XP, yes it is a glitzy version of 2000 that was made to be somewhat "idiot-proof". I know for a fact, that the same apps were running on each system(Norton2002 and Norton Internet Security). It isn't a decent comparison unless you have identical conditions. I run an Athalon XP2600 333mhzFSB 1GB DDR400. I don't know of any reason why it should operate differently under these systems. If I were to make a guess, I would say it would be slower under XP(even though I turned off all the glitz). It does use more memory than 2000, but with 1GB to work with, the difference is insignificant. I was kinda curious when my laptop(Athalon 4 1ghz 200mhzFSB with 320MB SDRAM) was getting decent render times. It runs WinXP. I keep both systems well maintained. In my experience, XP is faster, though I can't explain it.