Or more precisely, the xowiki compatibility matrix is your friend :) Thanks, AOLServer 4.5 is working well for me at the moment.
I didn't know AOLServer 4.5 was incompatible with OpenACS 5.0.4 and earlier. When upgrading I had an issue with the content type for text/html. This hack/patch enabled me to upgrade to OpenACS 5.2.3:
http://www.mail-archive.com/aolserver@listserv.aol.com/msg10006.html