If I install a new cpu will I need a new copy of windows?

[vincentily]

Or can i just use the one already in my hard drive?

 

[nukemaster]

Or can i just use the one already in my hard drive?

As long as you do not change the motherboard, Your windows install will be valid.
That is for OEM copies.

Retail ones allow you to swap anything you want(may still want to reinstall with board changes) as long as it is only on ONE system at any time.

 

[ss202sl]

Not if you're only putting in a new CPU. If you replace the motherboard, then you may have an issue.

 

[Kaluditz]

Make sure your motherboard supports the CPU.

No, you don't need a new copy of your windows.

 

[DizzyEgg]

Thanks guys.. My new CPU is supporated but I had to update my bios.