I'd go for 1024x768, which fits nicely in most widescreen monitors. BUT people can't comfortably read a screenful of text that wide, I'd divide that space into at least three columns. Two narrow columns with a wide one in the center works well.
I was very proud of the Website I designed for the women's center where I do volunteer work, but I got pushed out of the job. Our development director wanted something that would work on "smart" phones, and I couldn't design a site that looked good in both widescreen and smartphone formats. The new Website was designed by a high school computer class using Wordpress. It's OK, but I liked mine better.
-Joe-