IMO, ssd is something you only do if you have nothing better to do with the money. If you *do* end up getting an SSD drive, make sure it's a top of the line intel drive. They are shown to have the least decrease in speed over time.
I'd like to have two ssd's in a raid1 config, and do daily backups to a remote location.
I just got the new Intel 510 and it's a killer. Hopefully it won't corrupt my data like the old vertex 2 did.