moviemaking - issues

I somehow have the motivation to do a movie this summer, thererfore I have some questions, because my last 'trailer' was a failure and I want to make it a lot better this time.

Due to the fact that I have a 17' LCD, I can only record with 1024 x 768. The problem is, that I don't know to which size I have to resize the recorded scene. Which size would be the best?

The last time I didn't work with my nvidia-drivers, but somehow they're damn important to get a higher quality, so again, which settings do I need to choose?

Thanks for every useful comment, regards.