Windows 7: Can't install Windows 7 SP1 update

Ok so I currently have Windows 7 64bit installed and whenever I try to update to SP1 I cant. The reason why is because my original ac adapter was a faulty so I took to the geeksquad and they gave me a new one, but now my computer doesnt recognize the charger even though it still charges my laptop. Turns out the geeksquad gave me a dell ac adapter when my laptop is HP. So of course it doesn't recognize it. So now I can't update Windows7, my system BIOS or anything that requires my laptop to be plugged in to the ac adapter. So now my question is, do you guys of any possible workaroounds to allow me to install the updates even tho my system doesn't recognize my ac adapter? Thanks.

The best would be to get an hp charger.
I know no solution for windows to make it think that it is a desktop pc.

Hey I have an idea but idk if it'll work what if I take out my laptop battery, and connetct the ac adapter so its like a desktop.. do you guys think that'll work?

I think that is not that easy, windows has a pretty good system on determining if it is a dektop or a laptop, once it was installed on a laptop it will remain forever a laptop windows 7 though I might not be correct.