also with FL (and i assume most others) you can use qwerty keyboard to play live synths. only like two octaves at once, but it works for basslines, congas, etc. you can start rockin before you buy any equipment.
i got the drum pad one kicked down to me a couple months ago. it works well with fruity loops, after a couple hours of tryting to figure out the settings with youtube videos and shit. it's usually easier for me to just write the drums in step edit though. fun for sample triggering. i'm gonna try out the one with all the pots. should be good for tweaking synth lfo's and stuff. definitely good stuff for fifty bucks.
http://www.gersic.com/plugins/index.php?daCat=-3
this site has a ton of free synths, efx and drums in vst. works with most audio programs.