I believe it would be very possible. The 2.1 speakers should be amplifies already (most computer speakers are anymore). You'll just have to go to radio shack or somewhere to get an audio adapter. If you get a cable or adapter that goes from stereo RCA females(red/white) to 1/8" female, that would hook your speakers up to the standard xbox A/V cable. There probably isn't a pre-made cable setup that way, so you may need to get a couple of adapters together. If you need me to look up RS part numbers, I can tell you what to get. Most likely, the guys at RS won't be able to help unless you are buying a cell phone. (sad).
-Stobe