since 7.1 is not real (its a fictional 6th and 7th speaker) I say buy an Audigy 2 (24Bit with 196KHz/sec) with some Logitech Z640's (5.1) and your room is gonna shake like crazy!!!
I just bought the altec lansing 621's and they are great, i doubt they would have anywhere near the amount of bass as the z640's but the quality is amazing for. if you are not so restricted on funds, bet the altec lansing 641's (4.1ch) coz the sub has 2 6 1/2" drivers, and is the bigger than a midi tower case.
