If gaming is not your primary focus look into an iMac or MacBook/MacBook Pro. A little more but worth it if you can. If you want to buy a PC (laptop or desktop) go with Dell.
If you want to build a gaming PC check out my article from January. http://rsbb.ca/i4720 You should be able to build it soon since Intel has fixed the board issue.
I am under the personal opinion that dells are crap. As far as pre built, I prefer Compaq or Toshiba. I try to avoid dell and acer. Acer makes good monitors though.
As far as building them, I would recommend ASUS motherboards, good price, Great Quality. I would recommended Corsair or Kingston RAM, and nVidia graphics cards. I also strongly recommend AMD over
