When doing web design in photoshop, how large to I make the initial image?

I'm doing web design image to slice up in photoshop. how many pixels do I make the image I start with to cut up?When doing web design in photoshop, how large to I make the initial image?
I'd say the lowest common denominator is VGA





standard VGA size of 640 x 480 (pixel width and height)





that fills the monitor screen on standard settings with 72dpi resolution.





The browser is going to resize it anyway. Whenever I'm feeling around for an answer about pixel dimensions, I take a screen shot of a web page, crop the captured pic and open in Photoshop to see what the pix wide, pix tall is. Remember whatever art you do, save out at 72dpi for web graphics to get close to the 1:1 for what your artwork size was in Photoshop to look the same on the web page. Make something at 600 dpi and the browser will take a long time to download it. Open 600 dpi in a photo viewer program and the picture will have to be scrolled in both axis to see a ';knothole'; view.





I use the VGA dims for PowerPoint slides and on higher res monitors, it fills the screen with a good picture.