Measuring Pixels

I've done a lot of web design with photoshop. Often times it's best to make a large picture and then cut it up into smaller pieces to fit the spreadsheet layout of an html page, but I've always found it very time consuming. I basically have to make rectangle marquees until I get the correct dimensions, usually making a conservative estimate, then zooming in to slowly count the pixels needed. Is there a way to type in a pixel number to automatically select to that point?

Hi mosarani,
You can choose "Fixed Size" style in the Options bar and define width and height values. Then you just click on your image to select a rectangle.

Just in case you didn't know: in Photoshop / ImageReady (v. 5.5 and later) there is a special Slice Tool intended for cutting images to pieces. After slicing, just define output settings (slices may be saved to different formats with different quality) and use "Save for Web" / "Save Optimized" command to export all the slices and HTML code.

BTW, for the Slice Tool you also may choose "Fixed Size" mode.