I don't know much about AMD chips but it does look like the prcessor in the one you just put up (Apples) is a better one than the one Pete put up.....
But then, it's probably only the difference between Intel Celeron and Intel Pentium (most likely even less of a difference)
I wanted a P4 chip and 2.6-3.2 processor for the new family PC but coulnd't get one for the budget I was on, so settled for a Celeron 2.6... My mate hasa P4 2.6 (both identical PC's, just the chip is different) and whilst his is a little bit faster, the difference don't seem much.... I ain't really had a prob with the Celeron 2.6 in the new PC - this machine I am on at the mo is a HELLA old 667mhz Celeron

and this does me fine for web surfin!
Go with Pete's machine Lee - he knows his stuff and is a top lad for sorting you out with deals (plus the bigger HDD and screen)
Swapping it over to a new case shouldn't be too hard - just a case of remebering where the plugs all plug in (inside I mean) and swapping the stuff over bit by bit, then plugging it all back together again...
And there are some cool looking cases out there mate

That last one!