1) XP 1800+ is 1.53GHz, XP 2000+ is 1.67GHz......actual performance is very close and most people really won't notice the difference.
2) You need at least a 300 Watt power supply, although I'd recommend 350. Antec or Enermax are the recommended brands.
3) If you just want to wipe the drive and you're going to be installing a new OS from scratch, then yes, "format C: /q" will work. Basically all that does is clear the FAT.
I'm too tired to put any more detail than that. Hope that helps....
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