Personally I prefer HTPC, it can do more than any other single device. But they do cost the most (Caddy vs Pinto) and can eat up time tweaking them out the way you want them to be.

My 2nd choice would be the Xbox 360. Hands down the best multimedia console around. Since you don't have an HDTV you could even get the $299 version. It will connect over the network to your PC and play all the media you have on it. It's even getting IPTV capabilities later this year which is really cool.

2 cents

-Ben
HT v2.0
HT v1.0