Well no doubt any card you choose of those 3 will have significantly better sound than most standard sound cards on the market. if you wanna save money go with the audigy 4. I had an audigy 4 a while ago on my old computer but it burned out after the warenty was up. (god knows why)
The x-fi elite is better but for $200 more (after rebate) you tell me if its worth it. As for the E-MU i would know nothing about and have never even heard of the bastard, and with no ratings i would porbably stay away from it... just my thoughts