Topic says it all. Price range should be let's say $40-70. Needs to work as analog as that's all my g/f has, but if feasible, maybe a digital/optical option would be a nice bonus.
I have no idea what brand to pick from (Logitech? Altec Lansing? Creative?), and my g/f probably won't much care to have any premium kind of quality or brand. Anything will be better than what she has right now.
The setup should be two speakers and a subwoofer; I don't think anything more than that is needed unless it's more affordable than I think.
So, any ideas?