Between you and me and the fence post, I haven't found any decent games to play using Steam anyway. Portal has always had issues for me re:using the right mouse button (doesn't have any effect where it should position a red portal) and not matter what I do I keep getting stuck in a round-about loop that doesn't seem to have any way to escape it.
The reset of the games look like Win 98 models. Yuck.
I just remapped the orange portals to the "q" key.
Portal still plays fine for me. I don't have any other Source games (or any other games via Steam). Maybe my graphical standards just aren't as high? I've been playing it with the 9400M.