Web Browser simulators?

Anyone know a site that has simulators for various browsers so you can see what your site looks like under IE4/5/6 NS4/5/6 FF1 etc?

There's a site that a friend of mine has done which looks fine on their pc and on mine (with IE6 and FF1) but the client is complaining that on some PCs the form layout is all over the shop and unusable and I can't really understand what the problem is. Thinking it might be an HTML layers issue with older browsers so I wanted to check it out.

Michael.

 

Do you know how this site has be coded it may be worth trying to get him to validate it with W3C it may give a clue to what the problem is. I find that you get a site working perfectly in Firefox but not IE vice versa. Quite often it is somthing simply like in proper use of nested elements.

There is a site which shows you what it looks like by taking a screenshot however I cannot remember the URL for this.

I've created my final year project in pure CSS and used fix DIVs for positioning, this way I can guarentee it work with 95% of clients. I can't really suggest what the problem might be without seeing the HTML code, but I am very familier with this type of problem.