Can SCII be run on a widescreen monitor? I have tried various video setup's but it doesn't seem to work for me. The only way I can run the game is in a window, which is playable but very small. Any advice would be much appreciated.

You should be able to, at least, run it in fullscreen mode. On windows, I believe that's alt+enter, but I'm on a Mac so I can't test.

FYI, this game is so old that they never programmed for alternate screen ratios (or resolutions, even though "bigger" resolutions were available at the time). Consider the small size part of the experience :)

You can only make the game stretch to widescreen, but can't make it show more content horizontally because it wasn't programmed to.

To make the game stretch to widescreen:

1) Windows and Linux. Refer to this doc to find the location of DosBox settings: Dosbox.conf. Change the "aspect=" setting to "false"

2) Mac. In the program menu choose View->Use 4:3 Aspect Ratio

3) To run the game in fullscreen mode press alt+enter (win) or cmd+f (mac)