I created a set of company intranet pages using DW MX. I was very happy with the result too. However we have just taken delivery of some new Dell Inspiron 8600C's with Widescreens and now my pages suddenly don't look so good on them. Things in tables just are not aligned properly. Everything still looks good on older machines. Any ideas what's gone wrong and what can be done to fix it?

This is very normal when developing websites. You have to be sure that your website can be viewed in a wide range of monitor resolutions. Most companies focus on 1024 with 800 compatibility. But websites should also look nice on larger screens (1400, 1280). You have to adjust your table and cell width with combined use of pixels and percentages.

If you have e.g. a menu on the left side of the screen you probably would have a fixed widh, so you do this in pixels. If yout want to expand the website on you users screen you have the use the percentage.

But... also for the future: develop your pages in CSS!