Fugitive's links are good, probably the most recommended. That said, I agree with Bizman, and that's how I purchase me PCs. I've dealt with the same PC shop since 1997 in Calgary, MemoryExpress, they went from one store that focused on gamers/hobbyists to a chain of a dozen stores across Western Canada, and do it all now. They still have their gamer roots though, and have a team of builders that are fantastic - I now pay the $50USD to have my systems built and tested as the closest store is a 7 hour drive for me now, and in case of any DOA componenents/etc, that gets caught early in the build and 2 day test they put each box through, so it's worth it for me.
If you can find a similar sort of shop that has equivalent prices to everywhere else, and offers you the ability to pick your own components, and will build that for you, it's the best option IMO. That way you can customize your components and pick what you like specifically to be in your build. Warranties are usually offered, although be careful with this. I only purchase the MemEx warranty on high cost items like the MB, CPU, and GPU usually. Also the LCDs as they offer pixel guarantees, and the one time I've used warranty they had a new card - better than the one I'd bought - on the way the next day. The last build I only warranty'd the 2 GPUs and the LCD, nothing else.
