What older version? If you mean XP then you didn't upgrade at all but installed Win 7 as a new install, and so the hard drive now has two partitions, one with XP and the other with Windows 7.

If that is right, then you have problems because the BCD, the Boot Configuration Data, will be stored on the partition where XP is as it replaces XP's boot.ini file. If you delete the XP partition then Windows 7 will not boot.

As I understand it, this is not easy to solve.

Mark