Hawkeye22 :
Everyone says not to delete the system partition as that is where the boot info is. I upgraded from XP to Win 7 x64 using custom install. I disconnected all other drives before installing Win7. It did not create a system partition on my drive, so where is the boot loader located? There is only one partition on the drive and it's the full size of the drive. The only place the boot loader can be is in the same partition as the OS.
Sorry to necro this just wanted to clarify that in this case, the boot loader is definitely located on the same partition as the OS.
If you partition the drive before the installation of Windows 7 it will not create the pointless 100 mb partition.
Also, if you forget to do it prior and have to partition within the Windows 7 setup the trick to install the boot loader on the same partition as the OS is easy.
1. Create a new partition as you would normally and allow the setup to create the 100 mb system partition.
2. Delete the partition you just created, leaving only the 100 mb system partition.
3. Now click on the system partition and use the Extend option to increase the 100 mb partition to the full size or whatever size you like of your hard drive.
4. Format the now properly sized partition and that's it! Continue your install as normal.