Just a thought.
I am not a gamer.
Raid0 seems to show a nice jump in hd xfer rate.
Do the games you play hit the hd enough for this to be of value?
The only real answer might be for you to run your own test.
I have a feeling that game perf might be more based on proc/vid/mem speed then on hd speed.
These are my specs:
Intel 865p mobo
2.8ghz 800mhz fsb processor
2x512 corsair xms ram
ATI Radeon 9600 XT
120 gb SATA WD hard drive
I currently run Windows 2000 but i am going to reformat my hard drive and instal windows xp pro. My question is if its worth it to buy another hard drive now and RAID 0 it now since im going to instal windows XP anyways, or is it not even worth doing at all. I am going to be using it for mainly gaming.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic