Combining two PCs

Sorry, I might sound like an ass for saying this, but here goes anyways and you can skip this entire chunk if you felt like it:

 Spoiler

How are you going to merge two totally different PCs based on two totally different platforms together? Trying to shove a Celeron (whether it be a socket 478 or a LGA775) into a socket 939 board is like trying to take Mega Blocs and putting it together with LEGO. It won't work, it won't even fit. If you want to switch the ATI Radeon Xpress 200 over, good luck with soldering off a BGA chip and hoping that it will (and trust me it won't) fit onto an entirely different board.

And what gave you the notion that the Celeron is better than the 3200+? In the Prescott days, AMD processors were known to be 2x as fast as Pentium 4's of the same speed, effectively, faster than a Pentium D at the same clock speed. Though, they are not exactly 2x as fast as Pentium 4's, but the performance difference between it and the Celeron D should be negligible.

Well... I guess I'll end my rant off with 1 last point, why do you have E-Machines PCs? ._.

At any rate, I congratulate your effort; at least you are going about it economically.

Ok, now to answer the question.

The ATI Radeon Xpress 200 is built into the Northbridge, it is compatible with the Celeron D 330 in the sense that if it can be used to communicate with it if the motherboard was designed to use it (in case case, obviously not).

You CANNOT take either processor and just shove it into the other board, they are two completely different platforms (it won't go well at all, if you want to try though, be my guest).

The best you CAN possibly do is to take RAM out of one computer and stick it into the other, if they are the same speed; however, since they are not, the effort would be rather futile because for the extra 512MB of RAM you gain, you lose quite a bit of bandwidth (might be worth it if you are constantly running out of RAM, but otherwise, no). Taking the HDD out of one computer and sticking it into another would be one of the only other options. I'm afraid that no matter how much you try to upgrade (even if you could buy parts for it), it'll be at the end of its useful life very soon; that is, if its parts don't give up on you first.