Usually all sites open when using a different browser, its just the way that it is displayed that is an issue. Using good, clean code (sometimes a bit of hacking) does the trick.
As for resolution, 480 is being a lil wierd, I'd say 600 is a good place to start. So if you want to do it, set your table width and height (if tables are what you do) and nest the rest. Or simple set the div container width & height.
If you still don't get it, Shout and this time, drop (upload) some code.