I use Fruity Loops 8, but I've moved up to Nexus 2.
Fruity Loops is fantastic though. They have so many tutorials and stuff online, you can download sound packs, or you can make your own. It has something called
"Syntrax" which is a plugin you load up and it's a virtual keyboard with a zillion nobs.
Turning the nob will make it sound different, and it has a bunch of different instrument presets attached to it.
Piano, Sax, guitar, etc. (Yes, they even have a virtual metal guitar with nobs to adjust the tuning, amp sound, etc.)

When you get the sound you want, you put it on a thing called "Pianoroll" and adjust the pitches at the certain times.
It's 110% customizable, bro.

Go for Fruity loops.