I was curious, so I did some research into RAID0... Some points I took away:
* It looks like you'll be wasting space if you don't have two equally sized drives. You can only RAID the size of the smallest drive, so if you have a 160GB drive and a 320GB drive, you'll only be able to use 160GB of the 320GB drive as a RAID0 array. However, I don't know if that means you can still use the additional space as non-RAID space or not...
* The empirical performance gain isn't even close to twice as fast. According to this
article, it's about a 1/3 speed gain at best.