Windows 7: Old key reinstall WITH SP1?

I was wondering on the page win7 activation errors it says

"You can't use a product key for Windows 7 with Service Pack 1 (SP1) to activate a copy of Windows 7 without SP1."

I was wondering if it is possible to do the opposite though; To reinstall windows with sp1 using a product key that came with my computer where windows was installed WITHOUT SP1. Or will i have to find a Windows 7 copy of my version without sp1 to do the reinstall?

thank you for your time.

Welcome
It is possible to have a computer with Seven and if you have an CD with SP1, it can be used and you can be activited. If you do not have a CD with SP1, post and I or another member will get one for you.
I do not know of anyone who has actually tried this, however.

I made a bootable dvd using a ISO with SP1, however i dont want to use this if my product key wont work because the SP1 is included in the ISO when the key was originally used to install windows WITHOUT SP1 by the manufacturer and i STILL dont have Sp1 installed on it (it wont install, via update nor via manual install).

Thanks for your time

Downlaod and make an image with Macrium Reflect. If you do not work with SP1, use the image to reinstall, its free.
Imaging with free Macrium

I've been able to use the same keys before and after SP1 without issue.

Can you activate once you run Window Update to install SP1?

I didn't have any trouble using the key that was originally with sp0 to clean install with sp1 integrated.

Yes, you can do the opposite

A primary reason for SP's is to make a reinstall easy. You will not need to install hundreds of updates.

A service pack is a collection of updates, fixes delivered in the form of a single installable package.
So you should not face any problems in activation in any case weather you are downloading it through Windows update or you are doing a clean install of SP1.

Usually service packs include compatibility for new keys.