I know that most folks who appreciate multiple monitors are a little picky about their desktop, as am I.
For the past week or so, I've been trying out a nifty little free program called Gridy, that sets an invisible resizable grid to snap and resize windows to.
It seems to be working without issue with my Win 7 x64 Professional SP-1 with DF (including edge snap) on my dual monitor setup, and has a very small memory footprint.