From my experience I have about 1% of my visitors who use anything smaller then 1024x768 but the postage site has no reason not to fit into 800x600.
Use this in firefox:
https://addons.mozilla.org/en-US/firefox/addon/1985
That dude on the left of your loans page looks like the gayest douchebag ever, I'd look for a better pic.
Your top link on postage site is blue on blue, that's shit.