minimus

I am in the market for new speakers. I am trying to keep costs below 80 dollars but I want the most bang for the buck. Sound quality is key. I will mostly be listening to music (mostly jazz, classical, instrumental stuff.) I would like some boom for metal when I am in the mood though. Between the x540 and the z4 which would you suggest? I am using a laptop so probably wouldnt be able to fully utilize the true surround capability of the 540. Is it that big of a deal? I may buy an external sound card eventually. I am also open to any other suggestions below $80. Thanks,

Nick