My requirements are simple:

at least 2 GB RAM
at least 250 GB hard drive
Extremely kick-ass sound card

Can be portable or desktop. Stereo output would be excellent but not a requirement. Would like to spend as little as possible, as I will be using the computer primarily as a brain to control sound samples triggered by a high-definition electronic drum via USB port.

Don't know much about what sound cards are best or how to cut corners to avoid getting hardware/software that I don't need for this.