high end for gaming with most shit on max, mid for gaming with everything high and some mid, or low for surfing and general computer using?
I'll just throw some shit out there since I just built a PC and I've still got it all in my head:
Graphic cards:
High end: 8800gts 512mb, there are a lot of more expensive options but I don't think they're very good looking at price/performance
Mid: 8800gt 512mb
Low: 9600gt 512mb or Sapphire Radeon HD3870
the "best" brand as far as I know is EVGA, but they're usually a bit more expensive
Case:
High: Antec p182
Mid: Antec Sonata III case with 500w power supply
Power supply if you did not go with the Sonata case:
Any corsair brand power supply from their HX/VX series, the 450w is a good choice if you don't want to spend too much money; 520w is a good choice if you're looking for a modular power supply so you don't have to clutter up the case with cables; and the 620w is a good choice if you plan on having 4 or more hard drives for something like a raid system. They seem sort of expensive when I look at the price in USA stores though.

Processor:
Intel E8400 is what I would go with, don't know much about the quad cores and the budget ones though.
Mobo:
Gigabyte GA-P35-DS3L, DS3R if you want raid.
Memory: 2x1gb 800 (6400) memory of your choice, I like the Corsair brand the best, don't really know to be honest.
Hard drive: 500gb seems to be the sweet spot for money per gigabyte. Western Digital is a good brand but I don't know really.
And a DVD burner of your choice.