Actually, I'd try your luck with the DIY PC combos from NewEgg.
http://www.newegg.com/Store/MasterComboStore.aspx?StoreID=7&name=DIY-PC-Combos
Some of them aren't half bad actually, I know 2 friends that have bought different kits and have had success and good performance. There have just been issues with assembly, but you can always consult a PC magazine website for tutorials on how to properly assemble a custom desktop.
There are great advantages to having a custom system, but there will always be some drawbacks. For example, if something breaks down, you don't have a centralized company you can ship it to. You would have to be able to know how to diagnose problems...whether it be inviting one of your technologically advanced friends over, or doing a simple Google search. The good thing is that you can swap out (or add/remove) devices with whatever you want, and you won't be voiding any OEM warranty. You will also tend to get hardware that is very compatible with each other, and it won't just be some sort of "Frankenputer".
I started out in 08 with a Core 2 Duo E4600, 2GB of RAM and a NVIDIA 7050 integrated GPU, which was eventually taken over by 8800GTS. Then I made a switch to quad-core (Core 2 Q8200) in 09, added 2 GB of RAM (total 4) and swapped the 8800GTS with a 9800GTX+. My card saga in 2010/2011 included an ATI 5750, then an NVIDIA GTS 250, then finally I stuck with my current card the GTX 560 Ti. I switched over to an i-core system (i5-760) and had to switch to DDR3 RAM in 2010. My computer is a workhorse and has been through a lot. But that's the beauty of a custom system. You can make changes whenever you want, and your computer won't be out of commission for a long time. You can keep things up to current standards, and only pay a couple hundred greenbacks.
Just my two cents, sorry for the long story.