I've had a site with a domain registered in 99 about to be promoted more about to have its formatting totally rewritten to be more search engine friendly. Would it be better for search engine results to put the renewed site on the same domain or put it on a new one. It currently has PR3. My email address is made from this domain so it would be simpler for me to stick this one but if there is a huge advantage switching then I'd like to know?
Actually there have been discussions around the fact that older sites tend to have a little more leverage in the SERPs. I would definitely keep the old domain right where it is so that you can capitalize on the age factor.
If you know that domain is clean and there have been no penalities accessed in the past, then there is no reason to change.