When you install Windows 7 choose a custom install and delete the all partitions so the entire disk shows as unallocated. Then create one partition the size of the disk and install Windows 7 into that.
My choice would be to delete all partitions and format the drive. Leave the disc as unallocated. When installing W7 it will create the system reserved and C partitions it requires.
If installing into an already allocated drive, no system reserved partition will be created and the boot files will probably be on the C drive but could also be on any other drive on the computer.