Yes, definately put a SSD in there. The quality and budget of this build really screams that you put in an
Intel 520 Series 240GB. It really is the cream of the SSD crop right now and would be an excellent (albeit pricey) addition to your build.
If you're hitting the ceiling of your budget, I suppose a move to a
Crucial M4 256GB SSD would be a much more reasonable drive to put in (not quite as nice/fast as the Intel drive, but probably the best 'bang for the buck' drive out there).
Oh, and if you let them, local computer stores will rape you on prices. Try to find one that will pricematch with NCIX or NewEgg. Otherwise you're better off going with the big online retailers and paying shipping (buy all your components at once at one retailer and you'll vastly reduce shipping price).