Yes. Not hard to do if your site follows common conventions
of navigation. If you are attentive to detail you should be able
to do it in a way that pages of your site already indexed by
Google still are, just in your new format.
Mostly moving over to XSP will be a matter of pulling the content
out of your old site, removing some formatting information, and
putting it into XSP which handles formatting with it's own
Not that hard to do.