Windows Vista Vista SP1, Issue. Not booting properly.

Hello,

I started installing SP1 for Vista basic 64-bit version. Half way through the installation the computer was shhut down (roughly 3% of the second stage of instalation). Now when i boot up my pc I can only get as far a the windows loading bar, after that it runs some sort of check but get stuck everytime.

I've tried booting in safe mode, again it gets stuck loading the drivers. I've also tried the system restore but that dosnt seem to want to load.

I'm pretty stuck for ideas, I'm going to try booting from a cd but I have a feeling that's not going to work.

Any ideas? Theres some vary important work ive done over the last week thats hasnt been backedup.

Thanks in advance.