In c:\ you will find a file called Boot.ini Open it with Notepad and you will probably see both installations listed. You may have to reveal all hidden files and known file exensions in Tool>Folder Options to ee tis file.
Delete the one you don`t need and then save that file as Boot1.ini. (Files>Save as) In Windows Explorer rename boot.ini to boot.old and rename boot1.ini to boot.ini - Reboot
If you hit any problems an the way post back here.