Easy answer! My old "HTPC" that I used for years, was super basic. I just accessed folders to load movies via VLC. That's it :P
Trying to do it right this time. Using XMBC right now because it was the first real interface to try and using Assasin's guide. I'll probably try others too, especially when I have a real GPU. It'll take a while to figure out what I really like. For now, XMBC works fine. The built in scrapper is a bit touchy, but not too bad. I know that there is MCM to try too for that. JRiver is an interesting option for the future. Yes it costs, but it also seems to integrate well and takes a lot of guess work out with things like MadVR. Not sure I want to try WMC, but may. Also want to play with MPC-HC.