OK after another failed attempt at installing Mac OSX (OSX86) on my PC I ended up reinstalling Vista (grrr) forgetting that Windows loves nothing better than breaking GRUB making my Ubuntu hard drive (which I'd unplugged for safety) unbootable (or it could have been a throw back to failed attempts at dualbooting) either way I was getting the dreaded GRUB Error 2 message.
A quick google search brought up this stupendously simple guide to getting everything working again :-)
So pop over to Ramblings of an old man to solve your GRUB booting woes.
Oh and in a moment of weakness I themed Vista to look like Windows 7. Best theme I found to do it is by deviantartist Mufflerexoz and can be found here. I might even upload a screenshot in a bit.