I don't think the speed increase from 2.66GHz to 2.93GHz is worth it unless you've got the spare cash and want the best, or you're someone who will realise that extra amount in the time they save performing CPU-heavy tasks. For most users, the 2.66GHz is more than enough.
I think most people would notice more of a real-world difference by upgrading from a HDD to SSD drive.