A complete newbie needs a lot of advice!

Hey all,
Please excuse my ignorance, I'm a total newbie to this...
I'm looking for a pretty-much all-in-one package for creating music on my computer. I wouldn't need to do MUCH acoustic or non midi (ie guitar etc) recording, but some would definately be useful. I have a (slightly basic) midi-enabled keyboard and a brand spanking new Yamaha electric drum-kit (as I am a drummer and pianist) which could both somehow be used with the computer. As I said, I'd be writing mainly electronic music, and would need software which could let me do pretty much everything that I'd need. My next (and probably my main) problem is this: I'd need something not too expensive, as I am still at school, despite spending huge amounts of time writing and playing music.
What kind of set-up should I be aiming for on my PC (I have Windows XP if that helps), and how can I find out what the standards of my computer hardware are? Will my computer need to be pretty much dedicated to music?
My brother uses Cubase, but I've heard lots of people talking about Cakewalk and lots of other programs, are these the kinds of things I should be looking at? What are the pros/cons/prices of the softwares I should consider?
Anyway, thanks in advance for any help, and sorry if my demands are completely impossible and unreasonable!
A somewhat puzzled Ferdie