I'm running 1920 x 1080 (24" LCD) and 1280 x 800 (secondary, Laptop screen).
Are you designing a site for web developers, or web users? If it's for web users, then I'd be designing at 1024 x 768, or better still stick google analytics on your site and see what the current users are running.
As I'm sure you'll see in this thread, the audience on this pre-release forum software are typically web developers and will be running massive resolutions on multiple monitors.
Incidentally, anyone running a high res on Windows should definitely check out this superb open source window resizing app: http://www.winsplit-revolution.com/
Try moving your (Win) taskbar to a vertical position, I stick mine on the right hand side. Takes a day or two to get used to, but well worth it as maximises vertical real estate, can read the names of your apps in the taskbar, and can read the date in the clock.
Are you designing a site for web developers, or web users? If it's for web users, then I'd be designing at 1024 x 768, or better still stick google analytics on your site and see what the current users are running.
1280 x 1084 on my desktop but I design to 1024 x 768 as that is still the lowest common denominator of the general web users. http://www.w3counter.com/globalstats.php
And if you notice in that graph, iPhone OSX 0.81% and Android 0.07% which is why a mobile skin is so important these days. Also designing using html5 and css3 which is what this forum is based on makes logical sense.