Originally Posted by
DHorse
I do not think there is a solution to this yet.

The best thing to do is double click the title bar. The dialog will resize itself to it largest default size. (a Restore rather than Maximize state)

There is a
partial solution which has quietly been there in XP as well. If you hold down Control while closing a window via the top right X, its dimensions seem to be saved.
However, this seems to work
per application. This means if you do it for the Open dialog in Firefox, it's
only saved for Firefox.
A little quirky (well it
is Microsoft), but better than constantly resizing windows. Now if only I could get some Gnome windows to do this!