from the way i understand it THX wise, the only one worth going for is the THX Ultra2 badge, and thats if you are setting up a literal home cinema (ie a big room, lots of powerful hard to drive speakers, no neighbours and a 200inch screen...lol
i still love the THX badge for computers...makes me laff...heh...
for whoever it was just wanting an amp, get to a hifi shop, demo the ones listed in that thread linked above...try them out and see what you think, ask the shop if they got any more around the price, then buy the one that makes you think cooooool
for the one who wants amp and speakers, do the same....heh but for speaker recommendations, if u want wall mountable then your talking satellites, the choice is wide.....however you can wall mount bookshelfs if you want, then you get a better stereo performance as well if you take care on how you do it......best thing to do is start a thread yourself, list what equipment you already have, what your main prioritys are for usage (ie films over music or vice versa, what kind, blah blah....)
edit: ok, guy wanting speakers, u did list more info, lol, my memory gets worse......ok, go for satellites, thats a big room, M&K are good for kicking out a lot of volume to fill a space with movies, then get a nice fat sub to give the bass a chance......for amp, hmm, stretch your budget a lot and buy the top of range Denon, thats close to future proofing, it has HDMI switching anyhow..lol