I have no experience with pogo.com but is this game played in a browser window or does it run as a self-contained application?
What is your normal screen resolution?
If it runs in a browser window, then is the screen maximized (try hitting F11)? What browser do you use (XP had IE6, maybe IE7 if you upgraded, while W7 comes with IE8) so you may need to turn on compatibility mode? Have you tried Firefox or a different browser? Have you tried adjusting the browser font or text size?