Nah, get the MacBook Pro. The casing is much better, the screen is better and the processor might not be slower, depending on the models. Don´t care too much about the age, Macs last long. I´m writing this stuff on a 5 year old Power Mac G4, my mate still has a 4 year old iBook in everyday use. For gods sake: maintenance! A Mac will never be slower if it is maintained right. Get Onxy for your version of OS X. Use it to repair disk persmission and run the crons. After a restart your system should be fast again.