SSDs should only ideally be used as boot devices, as they all have a limited amount of read and writes to them they're not good if you're constantly transferring data too and from them.
In a top scenario you'd want only your programs that need instant boot up on the ssd (windows, photoshop, CAD etc) basically programs which usually take a while to boot up. And you should change your program files path to your HDD so all programs default there.
@ilsta, if you're a little confused by them just think of them as big advanced USB flash drives. SSDs are memory based (like flash drives), so have no moving parts - this means they're not limited by the spin speeds that hard drives are, however being memory based they're currently quite small in storage capacity compared to hard drives - so aren't ideal for storing all your games and such on.
Im still yet to buy an SSD, however when i take the wallet plunge it'll be an Intel i go for i think.