Bassist w/Cakewalk.....what else do I need??

I have the exact same setup. when I record the bass I go directly into the soundcard. then, add some of the standard cakewalk effects. try some of the guitar amp models, you can get some thick tones out of them.

 

if you're going to use a mic, you'll probably want to use a pre-amp. I use a Joe Meek EQ compressor, or my yamaha digital effects processer. just to boost the signal. but, I don't ever mic the bass, I just run straight from the pre-amp into the sound card. I can get the tone I want with a combination of the cakewalk effects, my pedals, the joe meek, or the effects processer.
remember any cakewalk effects you add will tax your system, so you'll want to keep them to a minimum. I'm running a 550mhz processer with 384mb ram but, one song I recorded had something like 13 tracks.

 

you wont need any special cable, but you will need an adapter. the soundcard has the small style input (like headphone style). you can pick up one at radio shack for a couple of bucks. then, you can just use regular instrument cable.

 

drop me an email if you need any help, I'll try to help with anything I might know.
pro audio 9.0 is an awesome tool, you should be able to do anything you want on there. if you wanted to record more than 1 track at a time (for drums or something) you can get a midi mixer that will allow you to record multiple tracks, and then still be able to mix it down later.