How to 'Update' a program

I want to distribute my programs. The only problem with that is updating or fixing an error.
I was hoping there would be a way for the program to check a website for a version number and then compare it to a number in the program code. If the online version is newer, I was hoping to download the newer version and have it replace the current .exe file. I'm pretty sure it may need to use the command prompt to move and replace the older file.
Of course, if there are simpler ideas, I would love to hear them.
Also, does anyone see any problems with my idea? For example, could a non-administrator account launch the command prompt?

I've moved your thread to hear where this type of issue is talked about.

Look here:
http://www.planet-source-code.com/vb...xtCodeId=69060
To replace a exe you have to be administrator on Vista