[H]ard|OCP has a guide on how to setup a nice system for Christmas, without totally destroying your food budget for next year.  TechReport has also given it a shot over here, and as always, Ryan’s recommendations can be found on the PCPerspective Hardware Leaderboard.
“For full systems, we scoured Newegg.com with budgets of $1200 and $2000 and looked at good buys for both AMD and Intel. For upgrade systems, we took budgets of $500 and $1000 and did the same. We’ve come up with good systems this year and we’ve even learned something for ourselves along the way.”