It’s as simple as this:
1. Open the Control Panel
2. Choose “System”
3. Click on the “Advanced” Tab.
4. Click the “Environment Variables” button at the bottom.
5. Choose the “New” button on either the User or System sections to modify the command prompt for just the current logged in your or the entire system.
6. In “Variable name:” put PROMPT
7. In “Variable value:” put ‘$g: ‘ (leave out the quotes, but leave a trailing space).
The $g maps to the ‘>’ character. See: Microsoft Windows XP - Prompt for customizing the prompt for cmd.exe
8. Click “OK”
Now Start -> Run and type: cmd and you should see your change. I also adjusted the colors to green and command prompt size to large to further make it similar. Hitting ATL-ENTER blows up the cmd window full screen giving it the most likeness...
Creating this effect for your account on a un*x system would be trivial as well by using 'set prompt = ">: " command. I don't have one handy or I'd try it out.