Oops!
OK, you need to find something that works on 64 bit.
You could try the Sophos anti-rootkit tool:
http://www.sophos.com/products/free-tools/sophos-anti-rootkit.html
I can’t guarantee it will work because it doesn’t give the system requirements, but you can try.
You could also try the AVG anti-rootkit tool:
http://www.freewarefiles.com/downloads_counter.php?programid=22524
Again, no guarantee it will work.
Or UnHackMe (Free working trial):
http://www.greatis.com/unhackme/
If you can access the HD from your secondary drive, you could run a scan from there. That’s outside my experience, but maybe somebody else could offer you some advice …