Installing retail copy of Windows 7 when you have demo versi

I expect I won't be the only person to ask - what's the best way of installing the retail version of Windows 7 if you have the demo version installed ?

Mine is on a dual-boot partition.

You can't do an upgrade, so you can either boot up to the demo and run the installer, this will keep non windows files on the drive you installed it on (normally C: ) and move the demo window files you a folder called WindowsOld.

Or you can boot from DVD do the same or format the drive so it's totally clean part from the new Win7

I did the latter.

Thanks, I'll give it a go !