How to assign monitor numbers in Windows 7

When I use 2 monitors, one on VGA and one on hdmi, Win 7 will always assign the hdmi monitor as 1 and the VGA monitor as 2. How can I manually assign these?

There is no GUI way that I've found.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Configuration

and more specifically

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Connectivity

are where Windows stores the mapping of the displays. It keeps track of monitors it's seen based on date and when if finds a monitor it's seen before it assigns a number. You can delete these two keys in the registry then reboot and the video card/windows will assign numbers to the displays using its default logic.

You can manually edit the registry keys and values, reboot and the system would keep the manually defined IDs however this is a rather painful experience and should be avoided without backups.

Apologies for bringing this thread out of the dead, I thought the information was worth sharing since I had the same question.

I have read this software allows you to change that.

http://www.realtimesoft.com/ultramon/

Depending on the Video driver you have whether you can change it in Video properties.

http://www.vistax64.com/vista-general/81095-changing-monitor-identities.html