mynameismolotov

Hey all,
I'm currently looking to buy a new laptop and I've mostly figured out what I want in it, the only thing I'm not sure about is the processor. It's a Dell Inspiron 1525 (which I'm getting because I get a deal on the warranty through my university). Anyway, here's what I'm looking at:

So originally, I was going to get the T5750, but then I was trying to learn a little more about bus speed, and one website (forgot which) was implying that it can be more important than actual clock speed. So I'm wondering if the 50 bucks extra (cost without upgrade is $1023) to up it to 800Mhz is worth it.

Also, and I don't know if this makes a difference, but my memory is only 667Mhz, so does that mean that having 800 on the processor won't be utilized? Or are these number unrelated? The exact specs on the memory are:

Thanks in advance for any help.