[Wardad]

Back on the cost savings subject...
Building your own is not a big cost saver.
BUT... it gives you control over your system, esp the software.

Buld your own and you can have the OS CD, and a CD for each application.
So the OS can go on a smaller C: partition and be easily reinstalled without affecting application on D:.

Buy a built one, and you may have to pay extra for the OS CD.
Your application and OS may be tied up in a bundled CD set.
Forget about selective reinstalls, you may have to wipe the whole HD and start over.