Doesn't look too bad to me. Personally, I'd toss the RAID0 config and get a larger single drive. But if you're not worried about reliability, eh, it'll work.
I would definitely keep the Raptors, they make a heck of a difference when used as a boot drive, especially since he has a raid 5 array for storage elsewhere.
except for gaming it is way overkill, you could do all the other tasks on a Duron and 512 MB ram. You could do all the other tasks with a P II and 256 MB ram. You could do all the other tasks on a Pentium 200 and 256 MB ram. Using Linux
OpenOffice on a Pentium 200? Maybe if you're into S&M. Sure, linux runs great on a P200... if you're doing iptables and web serving. My Celeron 300A w/128MB of RAM makes a killer web, ftp, and ssh server, but most DE's are going to be dog-ass slow by themselves on a P200, much less when running resource-hungry apps like Office stuff.
Anyway, the plan looks good, but personally I'd save a few bucks on the MB by going to a 6100/6150 solution and probably get a faster processor.