JMHO... if you really just want something that works, then the Logitechs will fill the bill... several sets under 100 beans that will give you decent sound, but if it were me and I was really willing to spend $100, I'd search (PriceWatch, etc..) and find a set of Altec-Lansing ADA 880's still left in someones inventory ... These are awesome 5.1's (front and rear left/rights, center and a monster sub-woofer) with absolutely amazing sound... A couple years ago when these were "the kind", they sold for over $300.
Good luck.