I was told that Win XP is better used with P4's, and Win 2000 is better used with P3's or older cpu's
Maybe whoever told you this was referring to using XP with all the eyecandy and visual features. And even if they were, I'd still say he was misinformed. PIIIs, Celerons, and AMDs Duron, all "lower-end" CPUs can run Windows XP just fine, and nearly as well as a P4 on otherwise similarly configured systems. Windows is not that CPU intensive, it is more RAM intensive. If you have a PIII with 512MB of RAM vs a P4 with 256MB of RAM, I would put my money on the PIII being faster, with XP or 2000. Also, you seem to be a victim of "Intel is better than AMD" propaganda. Sometimes this is true, and sometimes it is not. In some cases the P4 is superior and others the AMD. In the desktop operating system arena they are the same, and it doesn't matter in the least (other than in my previous mention of Hyper Threading). The Athlon XP can run equally as well as a similarly rated P4 with Windows XP, 2000, NT, 98, or ME. It simply does not matter.
\Dan