Fixing HTML to make them validator.w3.org compiant

Hello, I need some work done on my existing websites: a) pages need to be made compliant with [login to view URL] so that with 'HTML strict' they show no errors at all. b) pages need to be adjusted so as to display properly in all browsers (there are a number of pages which look good in explorer, but which do not look good in firefox. Both a) and b) need to be fixed by adding extra fiels to my existing stylesheet. The website has 85 html pages, and there are 6 versions of the site. As far as I can see, most of the errors relate to the same table and so once the main table(s) has been fixed, it should be relatively easy to fix the others. Also, page 5 in website 1 in pretty much the same as page page in website 3 for example, just the meta tags and sometimes the language of the text is different. So once page 5 for a certain website has been fixed, it should be relatively easy to fix page 5 for a different website. I'd be looking to get this done ASAP, but definitely within 3 weeks at the most. Thanks.