I was just assuming you had a Dell. Saying you're not smart enough to build your own isn't the way to go. If you'd like a great PC for the best price that you'd appreciate a lot more because you did the work, you should build your own. If you spend some time researching about hardware (reading these forums helps) and guides on how to build a PC, you should be able to do it.
If you get the time, open your PC and look and see if the motherboard is screwed down to the case or if it's permanently attached.