For Vista, you need to change the display settings to 800x600 with 16bit color.
To do this:

1) Close all applications
2) At the desktop, right-click the mouse
3) Select Personalise
4) Select Display Settings
5) Select the "Adapter" tab at top
6) Click "List all modes"
7) Select 800x600  16 bit
8) Click OK

You may need to restart the PC.