Question on upgrading Studio 1737 processor

Hi all -

Would appreciate any advice on this ...

I had a Studio 1735 which had the following processor:

Intel Core(TM) 2 Duo CPU T8100 @ 2.1 Ghz 2.1 GHz

Last week, it stopped charging its battery and running on AC power, so I read around a bit and found it may be the power charge board that was faulty.  I bought a replacement power board, but in case this wasn't the problem, or I wasn't able to fix it, I also ordered a replacement Studio 1737.

Turns out, I was able to fix my Studio 1735 with the replacement part and it's working fine now.

So now I'm left with two Studio laptops, hah.

As I mentioned earlier, my Studio 1735 has an Intel Core(TM) 2 Duo CPU T8100 @ 2.1 GHz 2.1 GHz. 

The Studio 1737 which I bought has a Pentium(R) Dual-Core CPU T4200 @ 2.00 GHz 2.0GHz.

I've already moved my two internal hard drives to the new 1737, but was wondering if there's any use to switch the processors, as my 1735 processor seems faster than the 1737.  I know absolutely nothing about the difference in those processors but thought before I resell one, I'd make sure I keep the better performing composite for myself.  Would switching out the processors have any noticeable difference?

Also, I'm running Windows 7 32-bit on my hard drive, but the replacement runs Windows 7 64-bit.  Would that be faster with a 8 GB of RAM?  I would just swap out the hard drives and keep the 64-bit but unfortunately I have long since lost my installation discs for the loads of programs I have. 

Basically I'm just wondering if there would be any usefulness of swapping out the processors.

Thanks!