When I plug in USB external hard drive and also flash drive they show up as devices but do not appear as an external device in My Computer. I have Windows 7 installed on virtual drive but set device to connect to virtual drive and disconnect from host drive. I'vr tried different usb ports and both devices work in host drive which is Vista.

Try going to the Windows Orb (Start), type diskmgmt.msc and press Enter, then right-click on the drive that is 'hidden' or unallocated > Change Drive Letter/Paths... > select a letter from nearer the end of the alphabet > OK and the disk should show in Computer. Try another letter if it stays hidden.

Mcurley - There's one possible caveat in all this...If you open Windows Explorer and press the ALT key, and select Tools | Folder Options and go to the View tab, there's an option that reads:Hide empty drives in the Computer folder.If there are no files on the drive, it won't show up. Make sure that option is unchecked.