Hmmm.....sound and USB....something I've never had to figure out. As most of my servers are in remote data centers thousands of miles away. Don't need to connect USB devices and don't have sound on my text only linux servers
I think that USB pass through was an ESXi 4.1 feature; http://kb.vmware.com/selfservice/mic...rnalId=1022290
Also, when you read documentation on ESX and ESXi, you will see some people taking about what ESX can do compared to ESXi. Well, vmware has moved away from having both ESX and ESXi. With 4.1 going forward, it's just ESXi and that's it. If you can live with the standard features and such, you can use it free forever. For any of the advanced features, you will need to license it and get a vcenter server up and going. For 3 hosts or less, you can get basic licensing with an Essentials pack for about $499. You won't get the fancy features like vMotion and storage vMotion though (this costs a lot more). But then again, most home users don't have shared disc storage anyway for this...so it's often not necessary.
90% of the ESXi boxes that I use are just the free ESXi variety. In our production environment we run ESX 4.0 with the full suite of features and it's awesome being able to move machines around on the fly without any downtime. But like I said, it's costly...to the tunes of 10s of thousands of dollars.