Upgrading

I'm planning on upgrading my pc from Windows Home Premium to Ultimate since I got tired of shit I can't do on Home Premium.

However I'm wondering, if for some random reason I fuck up and need to use System Recovery even if I already upgraded my pc, will I be able to keep using System Recovery?

Dude, I wanna user SR to changed the OS?
Think through just for a moment.

I just wanna update the damned pc since it came with Home Premium and I can't even add some languages properly or it's not reading some languages properly cuz of it. Getting tired of some games not working because of errors due to wrong entries too.