I Downloaded the Windows 7 USB tool, But could not find an ISO file that suits my PC. And what is the difference of SP1 and SP1 U?
The first part of the download page explains that, read after
New! Service Pack 1 Media Refresh (SP1 U) now integrated!
basically it contains more updates already integrated. Stuff done by MS themselves apparently.
As for the lack of your version... heh, forgot you are from norway. Sorry for that.

Just a little neat trick.
You will have to download a Professional 64 bit in your language, then open the ISO file with Winrar (or anything that opens ISO files), go in the folder "sources" and delete a file called
ei.cfg.
Then you make the DVD or USB drive as from the tutorial.
That file (you can open with notepad to see its contents for yourself, it's a bit of plain text) just tells the installer that it should only offer Win7 Professional 64 bit when your run it.
If you remove it, the installer will offer to install Home basic, Home Premium, Professional and Ultimate (all 64-bit). When you install you will then have to choose the one you have the activation key for.
Which if your profile is correct, would be Home Premium.
No, you won't be able to install Ultimate unless you purchase a license for it, this is just a trick to have an All-in-one installer, not a crack.
If you get a license for something else, you can install it from the same media as well.