If you have a budget of $600 then I highly recommend staying away from home theater systems. You would be much better off buying a component system. You can get 10 times the system that way.
Here is a package that include a Denon receiver and Boston Acoustic speakers. Part of the problem with "Home Theater" systems is that brands that make good receivers don't make good speakers, and vise versa (and that's only one of many issues with them). But this component package solves that problem and many more that the HTiB (home theater in a box) systems have. Denon is a highly aclaimed brand, and Boston Acoustics makes some very nice speakers. If you don't believe me, just Google the names.
http://www.google.com/products/catalog?hl=en&sugexp=ldymls&xhr=t&q=denon+home+theater&cp=8&qe=ZGVub24gaG8&qesig=vKYM9Ig2PI7fJ7miRPI05A&pkc=AFgZ2tljXvXAqp6VQlf0-WuJIPnAoJTNchuvUrLDixykPXd7WruJpXSqUGyPWkQ3d86AuRIJDTu40ygfkK-YSLvc3g40J_nzzQ&um=1&biw=1136&bih=528&wrapid=tlif129703399508610&ie=UTF-8&cid=15581860876130406796&ei=FCtPTeLfL8Gs8Aaps-WLDw&sa=X&oi=product_catalog_result&ct=result&resnum=1&ved=0CGEQ8wIwAA#
Now you just need a Blu Ray player. Here is a highly rated Samsung for $140. It has Wifi and downloadable apps.
http://www.google.com/products/catalog?q=blu+ray+with+wifi&hl=en&biw=1136&bih=528&wrapid=tlif129703424946710&um=1&ie=UTF-8&cid=17101388328180918315&ei=HCxPTYakHISs8Aa_pcDvDg&sa=X&oi=product_catalog_result&ct=result&resnum=2&ved=0CGMQ8wIwAQ#
So there you have a Denon receiver, Boston Acoustics speakers, and a Samsung Blu Ray player with Wifi, all for under $600. Of course with shipping, it might be closer to $600 even. But I can promise you that it will beat any home theater in a box system that you can buy for this price.