Laptop CPU upgrade, worthwhile at £14?

My second laptop, which I use because I prefer travelling with my cheaper one, I'm thinking about upgrading from a Amd Athlon II P340 2.2Ghz to an AMD Phenom II P650 2.60-GHz.

In terms of the cost, it will cost me just £14 and new thermal paste. The CPU is fully compatible - without a shadow of a date, and both are 25W.

I've looked at synthetic benchmarks and application benchmarks and there seems to be a small increase in performance between the two

So the new: 2600 MHz, 3600 MHz FSB, 256 KB L1 cache, 2048 KB L2 cache, 25W

The old: 2200 MHz, 3200 MHz FSB, 256 KB L1 cache, 1024 KB L2 cache, 25W

The upgrade price here is VERY cheap - so would you do it?