Those errors from TestDisk about superblocks - they only refer to the partition already on the disk, which is probably ext3 since Linux was on it. However, since the plan was to install Windows on that disk, there's zero point in worrying about that ext3 partition, since Windows can't use it and will expect you to delete it during installation. It's toast.
The only sensible option is to use fdisk on it, like mad_jock says, or a low-level format option. The Windows 7 installation is going to do this anyway, if it can, but I remember when I tried Vista a few years ago it couldn't recognise what was on a disk before and refused to wipe it - probably as a safety feature. I had to boot from a Linux "live" CD and wipe the disk. I call that the
Aliens strategy: take off and nuke the thing from orbit. It's the only way to be sure.
