As luck would have it, this month's PC Magazine (the November 2001 issue)reviews business PCs using either the AMD Athlon or the Intel Pentium 4. The AMD powered Systemax A1400RV Premier 1150 came out as best value for money but not the fastest by any means. It did use DDR (double data rate) RAM as well. Of course, Intel will soon launch their DDR version of the P4.
I've no personal experience of the two chipsets in competition. But the leapfrogging of manufacturers makes it difficult to judge when to take the plunge.
AMD has the price advantage at the moment and historically was better at floating point operations until Intel did some catching up. I may go for the AMD soon.
WinME was specifically for the games market and as you, like me, don't do games, you may be better going for W2K. However the Sony laptop that I use with ME and the Sony Digital Video software do go together very well. I suppose that's a spin-off from the games architecture.
XP is very well reviewed but it's more pennies for yet another upgrade before you've got your money's worth from the last one...