The MBR is used for a Windows 7 boot. But it is a 1024k (or something close) space at the front of the drive and does not show in Disk Management. If you want to check, look up hard disk and Master Boot Record.
The MBR does keep track of which type of OS you are booting to. For instance, if you loaded XP after you had already installed Windows 7, that install would overwrite the Windows 7 boot process. You would have to set it back to a Windows 7 process by using a command like Bootsect /nt60. If you wanted to make it an XP boot, you would use 52 instead of 60.
A repair CD is something you make. Go to Start Menu, All Programs, Maintenance, Create a System Repair Disk. This will allow you to boot into the Windows Recovery Environment in case the F8 key option is not working.
If you want to wait to see what someone else might think, always good to be cautious.