I recently purchased a Klipsch promedia 2.1 system. A fellow retiree/PC gamer acquaintance sent me his promedia 4.1 system, and I replaced the subwoofers in the 4.1, and replaced the front Klipsch satellites with a set of Polk monitor 30s. It sounds incredible to me, especially for gaming. Since my sound card is not very good, and doesn't have a very good crossover, the Polks are much better sounding, because more bass is sent to them than the Klipschs could handle.
Anyway. for the price of two replacement subs and the Polks on sale, I just love this setup. Now I need to find a good digital receiver to better control the sound, as my friend has 4 more satellites he's sending me. So I'll have TEN Klipsch satellites and the two Polks to play around with.
EDIT: Of course, I'll certainly need a decent sub to go with that type of setup.