Sometimes repair isn't able to resolve all problems itself vs. a fresh install. (Which is why you hear that method suggested so often.)
Where did you download msdart.dll? Just in case,
www.dll-files.com works.
Did you replace the copy in system32\dllcache (assuming it existed)?
Just so we're on the same page...
On another system copy the downloaded msdart.dll to a floppy, boot the problem box to the recovery console, copy msdart.dll to:
windows\system32
windows\sysem32\dllcache
I'll be around for a while this morning if you haven't already beaten this.