|its sounds like you have screwed your win 7 instalation.|
try a recovery with the recovery cd. try a system restore with the recovery cd, if all else fails, try a factory restore to vista then update to win 7 and copy your files over.
you do not need a third party partition tool win 7 disk manager will do most of what anyone needs.
you couuld also try easybcd,
did you not make an image of your system before you changed it?
you can reimage via the recovery cd too.
i hate computers!
but cant help myself....