|First you might consider a way to recover your data. Might try a linux live cd. A friend might have a Vista dvd that might work to recover your data. (not rebuild it) There is also a way to use some cd's of xp to get at data.|
I might also try safe mode boot. Press F8 at boot time. Could look at event viewer when you are there, if you do get that far.
Also you should never access your computer from an admin account for day to day uses. Make limited user accounts for that even for yourself.
"Best Practices", Event viewer, host file, perfmon, are in my top 10