Good point nichomach, does help if I'd state what I use the screens for!
I never play games on the PC, so gaming isn't important - though, that might change with Diablo III.
What I do have, is loads of applications open at once. On a daily basis, I'll have open two web browser windows, Dreamweaver, Photoshop, an FTP client, Outlook, Notepad, a few Messenger windows and possibly one or two other apps.
At the moment, they all just reside in the taskbar and I'm having to switch between them. I think it'd be far more productive to have more of them on screen at once.
I use Vista Home Premium, and the last time I dabbled with dual-screens I remember that the taskbar wouldn't stretch across the two screens - is that still the case?