www.hsuresearch.com
www.svsubwoofers.com
They are two of the most popular, best "bang for the buck" subwoofers on the forum. Very popular if your budget is $400-$1000 and want huge bass.
Can we narrow down the budget just a bit? Do you have anything that we can reuse? IE. Speaker wire, dvd player, rca or component cables...
What is your budget for a plasma? That will greatly reduce your budget for a high end HT setup. $3500? You should figure $100 for an HDMI cable and make sure the receiver has HDMI hookups. That will narrow your search on receivers. The Yamaha 4600 may be perfect. The Marantz SR8500 lists the HDMI in/out as DVI, which is different (video only). The specs are in favor of the Yamaha, as it's a tad more powerful and weighs almost 40lbs as opposed to the 33lb Marantz. Yamaha's are known for their excellent HT reproduction. Marantz may have the upper hand in detailed audio reproduction. Opinions will differ.
http://us.marantz.com/shop/_templates/Proddetail.asp?model=25&cat=15
http://www.yamaha.com/yec/products/receivers/RXV4600_specs.htm
Do you have room for a 6.1 or 7.1 speaker system?
Miller and Kreisel offer some of the best THX approved surround systems (bookshelf size), but are pricey. Take a look at the website.
First thing is to let us know what the budget is for the audio equipment you need. We can suggest some manufacturers so you can start the demo process.
www.mksound.com/Kseries1.php