In reply to Mark Torrance:
> (In reply to Siward)
>
> Good. Thanks. And my googling confirms this. i5 it is then.
>
> The money saved will go on character-bulding trips to sites of educational and historic interest.
This is simply untrue, some games only favour a dual core, but all modern games (pretty much) created in the last 3 years support 6/8 cores. It's a common mistake though which is probably why your google search showed it up.
For £80, I very, very strongly recommend going for the i7. I have the i5 you're looking at and it's not good enough for serious gaming. It's not bad, but for £80 it is well worth the extra. When I looked it would have cost £200 extra, hence why I went for the i5.