Windows can't read partitions for Linux so don't worry about that. Although I am wondering why you have a folder called Ubuntu under C:\... Anyway, Sounds like there is a problem with your grub.conf. Boot off of the liveCD and open a terminal and enter the following
> root (hd0,0)
> setup (hd0)
This should set grub up again. Hopefully this will fix the problem.
* if by chance windows doesn't show up in grub after running those commands do the following:
There may be commented out code for a windows install that looks like this:
# title Windows 95/98/NT/2000
# root (hd0,0)
# chainloader +1
just uncomment each line (take out the #) and that should get windows running again.
Hope it helps