I believe that Intel SpeedStep has an applet that works with both XP and 2000. As far as the memory goes, I just bought 1GB of PC3200 DDR RAM for my new PC for 80 dollars. I dont quite think 128 PC66 memory is quite worth 100, but it is still laptop memory (quite expensive). As I am too lazy too look it up myself, I suggest using
www.impactcomputers.com or
www.pricegrabber.com
Windows 2000 is definitely the choice here, as it is indeed no longer supported by our money-hungry friends at M$.