Resolving Resolution

Hey people,
I was wondering how to battle my current situation: I have made a site in 760 x 420 and it looks very nice at 1600 x 1200. What can I do to ensure that my site will scale down to the appropriate size ( the size I see it at on 1600x1200) when loaded on to a 760x420 res. I thought maybe if I made three different sizes of the same site and the slap some action script to determin the users screen res and call the appropriat swfs it might be possible. Is this the only methode and if so what script could I use?:h: