SA Window allows you to play SA in a window. This might have already been possible with other tools, but this one is different since it doesn't use a Direct3D hook. Instead it modifies game functions to allow you to select a windowed esolution. This is selectable from both the startup dialog box and the Advanced Display menu.
If you want a specific window resolution then first pick the fullscreen resolution and then select windowed.
Installation:
1. Download and install Delfi's ASI Loader from
http://alexander.sannybuilder.com/Files/ASILoader.rar
2. Put SAWindow.asi in SA root folder.
e.g. C:\\Program Files\\Rockstar Games\\GTA San Andreas
3. Enjoy.