Hiren's BootCD is a good multi-purpose tool for cleaning and repairing machines from an offline boot state. The link is here:
TDSSKiller is contained on the CD along with a ton of other free stuff.
Note that RootKit Trojans ("IF" you have one) are very difficult to dislodge and many of the anti-viral programs don't find them. TDSSKiller is specifically designed for removing variants of the TDSS RootKit Trojan.
However, since your errors occurred after a power failure (and based on your description of the problem) I would guess that your windows kernel or some of its necessary dll's have been damaged somehow. You should be able to repair those from a Windows Recovery CD, or by doing a reinstall of Widows Vista. Just don't format your drive and the install process should simply replace the damaged Windows files leaving your original file structures intact.