So I'm right near the end of the game. I just finished the second poker game and I'm following Jessie Bains up the stairs. I ran into one problem, though: the stairs won't let me up. I managed to get up on the first screen of stairs, but on the second screen, near the top, it won't let me get onto the top set of stairs. Now, I'm on a laptop that just has the standard up, down, left, and right. Do I need to be on a computer with the diagonal arrows as well? Am I just having an incredibly dorky moment?
Thanks.

Unfortunately yes, you'll get up there by using "7" and "9" on the Numpad.
Often there's a Numpad integrated in laptop keyboards, labeled in a different color (e.g. blue), which you can access by pressing and holding the Function key (labeled with "Fn") See here: http://en.wikipedia.org/wiki/Fn_key

On my computer i could use these 4 buttons to move diagnally home,pg up,pg dn and end see if you can try it on your computer.