This is a great server for general use. I have one and it's quick and has pretty much done everything I've thrown at it gracefully. It currently pulls duty as my Mythtv backend, Teamspeak 3 server, Minecraft server, and samba server. The one thing that it doesn't have is virtualization technology. Not really a big deal if you're only running an OS natively. If you decide to use Xenserver you won't be able to run Windows based VMs, but you shouldn't have any problems with ESXi. The remote server management is pretty cool as well, letting you monitor almost everything on the machine. Reboot, shutdown, edit your raid array remotely and all independently of the OS. Anyways, this is nothing new for anyone who knows these rack servers, but I thought I'd expand on it for the people who are considering picking one up!
It will run up to ESXi 3.5 the newer versions (4/5) need CPUs with the newer virtualization features. Even at 3.5 the free ESXi is awsome, I just never used it because it was so loud and it was more practical to use my workstation. If you have a basement to put it in it would be golden .. otherwise it sounds like a jet engine. There were some guides out there on quieting them down but I just did not take it that far.