750 wide is good Depends on the type of site also! More and more users are using mobile devices and net books Keep that in mind when designing your site!
1000px would be the max I would do. 720p+ resolution is common now days and it's pretty rare to see resolution above 1080p. One thing to consider is fitting in your ads so having a bit of extra width can help.
My suggestino would be to design your site for 1024x768..... I just wanna know whether min-width is supported in IE ? or is there some other ways of acheiving it ?
I usually assume 1024 x 768 as the default screen resolution, so a safe website is 980px wide. I prefer fixed layouts! Cheers! Jesse