Windows 7 can you reformat and reinstall Windows on the same HD after it's been activated?

[crashjesse]

Hello,
I am using Windows 7 Pro and I've had it for a year and my computer is starting to run slow. I would like to reformat the HD and do a new install so it's will run fast again.

Can I reformat the HD and reinstall Windows 7 using the same activation key? Or would I have to buy a new key?

 

[Trouble]

Assuming that you have a legitimate retail or oem, license (product key) and you are reinstalling on the same computer you shouldn't have any problems at all. The retail license is basically restricted to a single install instance and the oem is basically locked to a particular hardware configuration. So judging from what you've said above I would think that you should be well within your rights.
Backup, backup, and backup your critical data first.