If you are making a system for primarily bass heavy music, skip 5.1 and 7.1 and setup up a 2.2, 2.3 or 2.4 system. All the extra channels in a surround sound system isn't going to help any in a music system, but the extra subwoofers will help a lot, if you can set them up right. If you are on a tight budget and do not have the tools or time to build your own cabinets, Hsu and Rythmik are some of the best sub makers out there for entry level models. If you don't have a tight budget, check out Seaton, Funk, and JTR. If you want a massive bass system and have some woodworking tools, you really ought to check out DIY kits and projects. You can setup something amazing that will destroy any any commercial sub for the same cost.
As far as speakers go, that is more of a matter of individual taste, you should go out there and audition different models, and see what you like best. You can also just play it safe and get something that measures well for the most neutral sound, and one suggestion along that line I would make is check out JBL's pro monitor line, the LSRs. There are a lot of other great choices out there along those lines though. Don't just audition the hi-fi speaker brands, also look at pro audio stuff too.