Reformatting Windows 7 x64

It’s been awhile since I last reformatted my PC and recently its kinda laggy so I decided to reformat it. I have the original CD but the product key says single use only. and I’m afraid that after I delete the partition, it asks me for the code and i can’t use it
So my question is can I use it again?
Answer #1
You can install Windows 7 without key(you can simply skip that step). If your key doesn’t work use Windows Loader by DAZ to activate Windows!
http://forums.mydigitallife.info/threads/24901-Windows-Loader-Current-release-information
Answer #2
It will work as long as no-one is using the product key when you activate it.
Answer #3
huzibizi replied: It will work as long as no-one is using the product key when you activate it.
It all depends what kind of key he has…
Answer #4
Step 1: Windows Loader v2.1 x86/x64
http://www.datafilehost.com/get.php?file=5b457cda
Step 2: Validate Windows (Use Internet Explorer)
http://www.microsoft.com/genuine/validate/