get massive surge protection, the kind that will actually melt down in case of a lightning strike to protect your gear. For speakers, i'm a fan of the powered studio monitors that mackie makes...
http://www.mackie.com/products/studi...ors/index.html
for main systems, it depends how much you want to spend, there are some 20,000$ pieces that upsample everything to 192khz and pump it out 96khz sampling rate to each channel... those speakers weren't cheap either...
after the mackie type price range, it just seems to get so insanely expensive for improvement (cause of lack of mass production) that I don't really follow it closely as i'll never be buying it... if you want true 3d sound for the entire room (versus 3d sound for one pinpoint spot in the room), you'll need about 300-400 speakers, and 15k$ to license the tech
sorry i'm worthless.