I need a simple code to check wether the screen is smaller than 800 × 600?

I have a game that needs to be in at least 800 × 600 mode and I need a simple code that will check the screen size and then change it if nessasary, and then if it has changed it, change it back again to the original settings? can anyone help?:confused:

There's an article on resolution in the actual VB-World site, look at the tabs above and click "Articles".