I been using Raid for a decade now... Or I should say I was...
Raid was really useful when HD's were small in size and I used to have many systems with 4 HD's hooked up in a stripped array to get 12 gigs on line
But its a major headache.. In some cases 2 drives will speed up stuff.. Since the IO is done by 2 different drives... But not always. Having 4 drives did speed up stuff but the heat and power requirements were huge since all 4 drives had to work at the same time. But also the drives used smaller caches and IO was slow as well.
After seeing India, I have to go with reliability should be priority #1 in any case. IE anything that reduces reliability should be discarded. Using 2 drives mean it takes more power and more load on the UPS and less backup time. Also means more things that can go wrong. But not only power but the climate and environment are very hard on equipment.
So unless you want a Triga Byte storage system, just use single drives.. The are now available up to 400gigs per drive.. And SCSI and higher RPM's also speed up stuff, Not for sequential file xfers but for things like compiling a large program or database.
If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer. The real world performance increases are negligible at best and the reduction in reliability, thanks to a halving of the mean time between failure, makes RAID-0 far from worth it on the desktop. Bottom line: RAID-0 arrays will win you just about any benchmark, but they'll deliver virtually nothing more than that for real world desktop performance. That's just the cold hard truth.
*www.anandtech.com/storage/showdoc.aspx?i=2101&p=11