Don,
Oh, not to worry about that. This is only a play-with-it site and I have backed up the db at every stage!
It may be a CSS clash, but it could be more fundamental than that. I notice that if I edit the default index page the >>left-col<< open and >><< close tags have been replaced as >>left-col<< and >><< respectively.
If I try changing them back to >>left-col<< and >><< they are then simply displayed as verbatim text on the output page rather than being interpreted as tags. I have tried submitting this as simple text and also as html.
If I switch to the Default OpenACS theme, the column layout is fully respected.
If you have fixed the page displacement issue and a fix can be found for the XoWiki admin links, then perhaps it would be better to recommend the Default OpenACS Tabbed theme.
R.