ajax/jquery

Hey guys,
Basically, i just wanted some advise on a project that i am working on
for a big client of mine.
Ive got a folder full of notes regards to accessibilty and how to make
the website fully compliant.
The problem is, that we decided to use ajax/jQuery to provide alot of
the functionality on the website, but i am still searching around if
ajax would be the way forward if the client is wanting a 100%
accessible website.
Nothing from me has been coded yet, and its just ideas that i am
researching on at the moment, which ajax was mentioned.
My question is that, is there a backup plan if i did code the website
using ajax using jquery but if js was disabled then how would it
function. i.e. rather then the ajax call passing data into a div, the
page would reload and take the action it needs to.
Hope that makes sense and any advise/tips and tricks would be
greatful.
Thanks
Raj