What window size?

I’m developing a training demo in Flash and I need to decide how big the window should be that contains the demo. I’m not privvy to such best practices considerations.

Any advice on this? I’ve tried 800 x 600 and that seems pretty small. I started with 1024 x 768, which works on my work monitor (which I dock my laptop to) but is too big for the laptop itself, and my laptop has a rather large screen.

900 x 712 seemed like a nice compromise but not standard. Either way I think I’m looking for a 4 x 3 aspect ratio, correct?

Thanks!