I have never used a SSD but they do sound nice. The main negative I have heard is that a SSD may not stand up to as many read/write cycles per unit space as a standard HD does. Since they are relatively new, this may or may not be true - standard HD's usually work fne for a long time. If I were doing it, I would likely put the programs on the HD and rely on a std HD for the working files.
Installing the OS & SW (and other "can't live without" software) on the SSD makes for fast startup times.
Wherever possible, keep all volatile data on the HDD ... or a second SSD.
FYI, never defrag a SSD.