Windows 7 does not go after formatting

Hello,

I had windows 7 on one partition and windows Vista on the other.I wanted to remove the Windows 7 OS for which i formatted the partition on which it was available.

Now when i start my laptop , the start up screen still shows the options for both the windows and when it goes to Windows 7 , it gives an error ...system could not access the required device ..".
What do i do to completely remove it (though i think i have removed it cleanly enough so that it should not come back) and my system can directly pick up OS 2(i.e. Windows Vista).
Please help