You didn't delete the existing partitions before installing.  You can alter the boot list by installing EasyBCD.  You might have the option of changing the list by right-clicking [My] Computer, Properties, Advanced System Settings (on the left), Startup/Recovery, System Startup ... or by going to Start, searching for MSCONFIG, and the Boot tab. If the "problems" you were having previously, which led to your reinstall, may have been caused by disk/file system corruption, then I would recommend reinstalling again and deleting/formatting your disk before the install.
Due to a problem I had on my Laptop, I did a Clean reinstall using the custom selection on the win7 cd. All seems to have gone ok, except that when I boot up, I am now given a Boot screen on startup where I am asked to select which operating system i want to boot with. There are two Windows 7 options. What Did I do wrong? thanks  
Reinstalled Windows 7