First Vista problem? speedstep not working?

[caravel]

Well, here is the page for BIOS upgrades for my current board, I think my BIOS version is 1.5.

You need to be sure which BIOS you have currently and which board revision you have. There appears to be no revisions to your board, though it's a good idea to make doubly sure of this.

I've done a BIOS upgrade with a simple flash tool before, it allowed me to do it until there was no error found, but it was a tool from AOpen and it was old.

Having to make several attempts is not usual. I would suspect that you were trying to do it from windows (?) and a background process may have corrupted the flash process.

I still don't have a Floppy drive, so making a boot disk or backup disk would be a bit hard for me. The notes on what they fixed are a bit short for my taste, they could include what I want or not, but a somewhat detailed instruction how to do it, which looks as easy as that AOpen thing, if not easier.

If you have a USB flash drive you should be able to boot DOS from that and just place the flash image and tool in the root of you C: partition. I would avoid the windows based flash process like the plague. There are sites that allow you to make boot disks, typically you'll only need command.com, msdos.sys, io.sys and two empty text files called autoexec.bat and config.sys to boot to a basic dos prompt the rest of the files that the bootdisk containes won't be necessary.

The problem is, I'm an idiot, so if I will screw it up I am going to spend 200EUR for a new NForce6 board, I just need a reason.

Well have you looked at any other possible causes? If it's not working in Vista but was working in XP is it not possible that Vista has broken support and that upgrading the BIOS won't resolve it.