Infopirate.org

Hi Guys. I am new to this forum, and new to vista, so forgive me if i ask stupid questions, but i have gotten an urgent problem.

I have somehow gotten installed some Grub booting up before it then tries too boot up Vista, sometimes, while still in Grub, displaying the message File not Found, and other times it manages to get to the windows menu for selekting safe mode or normal mode, but either way, it freezes and will not continue too boot.

Anyone got a tip on how to remove this?
I have allready trying to insert the disc, and sellect repair, but that doesen't work.

I built my own computer and it is my main computer , What I have read is OEM means one time install, this may be some stupid questions but I Need to learn, OEM is just for one computer so say i get a virus and reformat i can still install that OEM on my main computer correct? Also what is the price for OEM vista home premium (non upgrade)