Well anyway, this is the order I learned to install 'hardware' (random misc peripherals excluded):

-RAM
-Hard drive
-CD drives
-power supply
-2ndary/multiple fans
-mobo

The motherboard was last because for the longest time I thought that it was difficult to install. Notice that I didn't include 'processor', because I think it typically should be installed by a professional. Anyway, the point is that everything in the computer should be easy to install, so I have no idea why you would resort to a packaged computer. Hope you got a good deal though. I think a good price nowadays is about a grand? (but would lack a lot of things ) *shrug*