Meta tag Problem

Meta tag Problem


Dear Folk,
I've developed a website with ajax capabilities and bookmarkable
supports history,
I would like to give a specefic Meta tag to each page ...
what is the solution ? there is two thing in my mind
1- upgrade the meta tag with jQuery when each pages loads ...
for example
$("meta[name=keywords]").attr("content","a,b,c,d");
but as you all know when the page loads meta tag is something else
after that with ajax will be upgrade so I think this may cause some
problem in search engins ....
2- load another meta tag in the page ....
and this might cause two meta tag in a single page ...
consider there is shopping cart in the web and when each of the
Products nloads the title of the page changes and their own meta tag
came in so does anyone have any idea on this matter
at the end I aim is for me to make my page reachable in search
engines
as google and Yahoo
Kind Regards Pedram