The first few times I installed Windows 7, I noticed that it created a hidden 200MB active partition on my primary hard drive. The purpose of this partition is to store the boot files and the Windows Recovery Environment (WinRE) for repairing your computer if necessary. Once it is created, it is very difficult to remove and you risk your computer not booting.
Now this is a good idea in theory and for most people, this won’t matter. But when I am setting my my systems (at least with Vista and Windows 7) is that I install the OS on a machine and configure it exactly the way I want it. I then install all the software on it and take an image of it using Acronis TrueImage. I can then take that image and setup a new computer (with different hardware) within a matter of minutes.
This whole 200MB partition deals complicates the imaging process and so I looked into the details of it. Apparently if you install Windows 7 on a drive with unpartitioned or unallocated space. Create the primary partition first by choosing Drive options (advanced). When you get this dialog box: “To ensure that all Windows features work correctly, Windows might create additional partitions for system files.” Hit Cancel. The boot files will now be put on the primary partition that you created earlier.
If you aren’t going to be imaging your system or you want to setup dual boot, you can go ahead and let Windows 7 do it’s thing and create the extra partition.