Yeah. if you have $$ to burn, going with 10K rpm drives are definitely better. And if you have even "more" $$ to burn, go with 15K rpm drives
. That'll be even more better..
It all comes down to purformance vs storage. If you go via the 15K route, you'll spend quite a pretty penny (and I mean a very shiny golden penny). And unless u are running is database server, is probably not justified.
For the same amount of storage as ur 7200rpm drive, if you go via the 10K rpm route, you'll easily spend 3-4 times the amount on the 10K drives.
As I said before, if you can post a list of ur apps, I think ppl can help u better.
I've known ppl who've spent > $3000 on harddrives alone for a single computer. I am sure u don't want to go via that route