I have PC running Win 7 64bit OS, Some time back i have installed VMware and allocated around 70GB. I have uninstalled the VMware software, but it did not release the disk space. I ran spacesniffer and it is showing this space as Unknow.
You need a partition manager by the sounds, This software is for Virtualization Software for Desktops, I think it would have created a separate partition to run off, Download Network Magic and Delete the partition if it exists, and merge it into the default or main partition that you are using..
This software is pretty user friendly, but let me know if you get stuck