I'll throw in my two cents here as I have some experience in both music and HT..
First off I am more like you, more music listening than HT or anything else. I find myself now to actually be 99% music 1% HT, whereas before it was about 80/20. Even when I do watch a movie surround just doesn't do much for me. Yeah, it's cool but there are three extra speakers that need placement, which will also mean 3 extra sets of reflections bouncing everywhere. The room becomes even more critical in a good HT set-up versus just music.
Not only that it's more expensive, HT amplifiers do not do music justice like a good two channel will, and so on and so forth (at least on a budget anyway). Now on the other hand if you are into DVD audio, then a surround set-up will do you a lot of good! That's about the only reason I would suggest to go that way.
Otherwise, if you are a primary music listener, invest into that. You could go both ways and get an HT amp with a 5.1 set of speakers and then buy a two channel amp and use the pre outs on the HT amp into the two channel, which would realistically give you the best of both worlds, but certainly makes the set-up a lot more complicated and if you use vintage equipment for the two channel you are gonna have fun getting up and always changing the dial on the two channel amp when you integrate it with your HT set-up.
So in the end, you have to ask yourself - do I care for the surround effect? Do I have the money for it? If your answer is no, then don't worry about it. Do it later on when you have extra money lying around and a good room to put it in, or if the wife wants it or something like that. For right now, it sounds like you should go with music. Although everyone already suggested that, I thought I would just throw in my two cents worth.
Now with the .1 part of 5.1, if you do go two channel I would strongly suggest just going with two speakers and no subwoofer. Add the subwoofer after if you feel it's necessary. You will need to ask yourself though if you want a vintage amp, or if you want something new because almost all vintage amps do no have a sub pre-out. Personally, I went with floorstanders and no sub and I think it is far easier to work with and better musically than using one subwoofer and two speakers. To get the most out of a sub you need two of them.
