convert asp.net site into new css tables stylesheet

We have a website using ASP.NET and c# and vb but it currently uses tables and does not fit the whole browser we would like it re-worked to use a css tableless design we already have to ensure it fits the browser, the code may need changing in places as it may have table structures e.t.c within the code and will have to be changed to suit css the website uses 2 masterpages for the main template with individual pages into this thanks very much