Re: Buy new or Mod old?
If you don't feel comfortable building one you can cheat. Take a picture of your current setup, look where everything is and such. Then buy a new case, a new PSU, and a new graphics card, if you need get RAM. Now what you do it you unplug everything, and carefully move over your motherboard to the new case. Then from the picture you can start hooking up stuff.
Make sure your motherboard has a stand-off from the motherboard tray so it doesn't short.