1 tip on firebug
Web Design in Firefox, Tweak for IE
When designing a website never use Internet Explorer to test your pages with. Allways use Firefox.
There are two main reasons for this:
1. Firefox renders more closely to the w3c web standards than IE does (by miles)
2. Firefox has lots of neat plugins to help you test your designs (Firebug for one)
Once you have tested that your web design is perfect in Firefox you should then tweak or hack your CSS to work for IE. Firefox is definitely the web designer's friend.
We all know IE is a law unto itself so don't be a slave to it. Design your website to the correct standards first - Always!