WML or XHTML - What should I use for a database driven web sites for mobile phone?

The back end will be PHP and MySQL but I am not sure what front end to use. In the past I have made sites work perfectly on mobile phones by using W3C standard XHTML and complying to WCAG AA standards. Good use of CSS then makes the site looks good on PCs.

However am I right in thinking that older WAP 1.0 phones are not capable of viewing HTML in any form? I have a book on producing sites for mobile phones but was published in 2001, and things have moved on some what.

My gut feeling is that XHTML would be better as only one site PDA/Mobiles and PCs would be requried, also its likely that anybody who uses WAP of any sort would have a WAP 2.0 enabled phone anyway with a basic form of HTML browser.

Thanks for any input on this. Creating this site has become more difficult than I thought as I can't have any query strings etc, I have sorted that now though. The site is just a front end to a MySQL database.