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#41
The disk carries the same factory SLP preactivation that the PC ships with, so that the Product Key on the COA isn't used and if you use a keyfinder it will show a different key only valid for activation at factory.
So with any other clean installation DVD you'd activate with the Product Key on the COA sticker, but on your specific PC it carries the SLP factory activation file that sets the activation (at least) back to Factory condition.
Everything else is like a Clean Reinstall Windows 7 except for a Dell Logo on the System page.
Be sure to keep that disk. I'd even back up the ISO file using ImgBurn. But the best way to back up so that you never need to reinstall again is to save a backup image externally so if Win7 becomes irreparable you can reimage C in 20 minutes.