A few more back yard flights under my belt now and still loving the kk2!
Andy - USBasp flash tool is going in the post tonight (2nd class - the only stamps I have!)
There are plenty of "how to's" out there, but this is the one that I used:
The hardest bit is getting the driver to work. Some people are having trouble with the older USBasp tools and windows 7, but this laptop is win7 64bit and it all worked fine.