Do you use Netflix? A while back I bought a Zotac Mag to have as my entertainment center. I set up Ubuntu on it, my usual dev tools and Boxee. I found out that there was no way to make Netflix work on Linux, other than through a Windows VM (which the Mag's cpu couldn't deal with).
Because I had to have Netflix (my wife uses it all the time) I took the Mag to the office and bought a used Mac Mini on Craiglist just for this.
Why didn't you just loaded Windows on the Mag? Windows 7 Media Center has one of the best Netflix clients I've seen. Also Boxee on Windows will do Netflix, although last time I tried it the Boxee version of the NetFlix client was really, really shitty.
Because I had to have Netflix (my wife uses it all the time) I took the Mag to the office and bought a used Mac Mini on Craiglist just for this.