Probably easiest to boot some kind of recovery media. https://skydrive.live.com/#cid=B0A22...89320E3247!345
d/l REP.7z from the above link. Use 7.zip to extract it and you get REP.iso burn iso image to cd ( or put on usb stick - if you can do that )
Boot it up.
If you have any data you need to save - copy it off somewhere - to another partition or to any drive you can see from the boot media you just booted up.
Find the Windows 7 partition and quick format it.
Use Gimagex >Apply Tab >SOURCE- browse to factory.wim>DESTINATION- browse to Windows 7 partition.
Should only take a few minutes.
Then use NT6REPAIR Auto boot repair.
Select Active partition, Select Windows 7 partition, then click Apply.
Restart and you should be ok.