To tell the truth, I can't really tell the difference between this system and the 2.8 Celeron I had before. They are both so much faster than my previous system it doesn't matter.
You will not be noticing that difference for quite a time as well. The frequencies of the two CPUs are really close. However it is obvious that AMD has enormous cache compared to pity Celeron. But when will be the absolute difference ?

You will feel that you invested on the right stuff when all computer programs move to 64-bit. It does not matter if you have a 64bit 7.5 GHz CPU when you run 32 bit OS and programs (ok ok,it will be fast actually). The CPU can run this previous level of programs, however it can show out its power when your OS and programs are 64bit. Windows XP has a 64bit version, you may give it a try. However, such system will only look for 64bit drivers as well. A computer geek's job.

So why the need for PCI-Express?
Annoying elements of Capitalism.. They made PCI bus video cards obsolete years ago, and since they have to shake the motherboard market, they release that PCI-express thing. Believe me they have already developed the next two or three levels of bus technology. It's all about keeping the market vivid. I do not think a smaller slot and 16x bus is worth changing the whole motherboard. Vampire job..