There is a ton of information here:

http://www.dfi-street.com/forum/show...ighlight=raid0

if your are doing lots of large files, large strip. Small files, small strip. It also has a lot to do with your disk drives formated sector size - windows default is 4k. For two drive raid, they where finding that a ratio of 1:4 (cluster size to strip size) was optimal (i.e. 16k)