well, i have to say that if I were buying A SUB, it would be only from one brand. that brand is velodyne. i would buy the best that i could afford, best being Digital Drive 1812 Signature Edition, however it costs over $5k i think. next would be DD-18, then HGS-15X. i currently have several HGS-II 18s, which incorporate everything the newer models (except 1812) do except for the parametric eq feature, same amps, same driver, etc. i will NEVER go to any other sub manufacturer unless velodyne goes out of business. i have used them for years; i will use them for many more. they always get glowing reviews, they have good people working there, and they are reliable.
anthem makes an AVM20, coming out with statement D1, which i think is best pre/pro money being secondary.
i would probably give outlaw amps a try, m200s are my style. rotel is nice too though.
as far as speakers, i am not as interested in them, so i dont keep up with a lot of brands, so i wont waste your time.
dvd player=DENON, whatever one you want. if sacd is important, then the 1200, if not 910 (which is what i have). keep in mind dvd is soon going to be revolutionized with blu laser technology, so dont waste your money now.
niles make good distribution systems.
cables, there are a lot that are fine. buy a good sub cable, buy good analog cables, and buy good speaker wire. video and digital i have found to have smaller quality gains with significant price gains.
THE SAMSUNG DLPS ARE JUNK. if you must get DLP, get a front projector using 3 chip setup (there are several brands that are good, runco being best, but too much for the 15k range im sure). unfortunately there are not too many 50in tvs to recommend, they all have serious issues, hence my suggestion for front projector.
hope that helps you out some.