With $1K for everything else, I'd spend $750-800 on speakers and $200-250 on the receiver (Pioneer or Onkyo, GottaDeal has a $186 Pioneer today).
Every dollar counts for speakers until you get up to at least $1,000 while you won't hear a dfference between a $200 and $500 receiver unless you do spend more that that.
$3K is just enough for a Samsung 50" 1080p DLP with 4 year extended warranty from Circuit City (+ tax

), maybe you can pricematch elsewhere to get it under $3K including tax.
Or buy mailorder, preferably from someone reliable like Crutchfield or TVAuthority. AVSForum had a power buy with TVA to save $100, not sure if it's still on.
Cables: DO NOT buy cables from a chain store, don't buy a power conditioner either. Just get a nice surge suppressor from Tripp Lite or APC for $20-35, and get cables from someone like monoprice.com for $15 instead of $100 monsters.