the 3200+ is IMO the best CPU for the money; it has a winchester core, so it is 90nm, uses less power, runs cooler, and overclocks better
a Raid 0 will not limit the disk space you have, it combines the total space of the 2 drives
a Raid 0 writes half the data to each hard drive at the same time, thus increasing read and write time
if you do get a Raid, do not use software to control it; it ends up being unreliable
a hardware controlled Raid is much better than a software controled Raid, it also makes it a bit faster (due to less load software wise)
for the motherboard: I would get an Abit AV8 3rd eye, it is a good quality board, less expensive than the Asus A8V, and it is designed for overclocking
as far as RAM goes: Corsair is way too expensive IMO, Kingmax has good quality RAM, at much lower cost than the Corsair
you can get a gig of PC3700 (2x512) for $79 at newegg, which will perform better than the XMS RAM, and be much less expensive
in reality, low latency RAM makes very little difference
corsair's PC3200 XL RAM at 2-2-2-5 timings only gets about 4% better performance than their value PC3200 RAM at 3-3-3-8