I’ve upgraded to the latest version of WordPress and started updating the theme (it was so old it pre-dated widgets and so kludged together that it has three different ways of producing the same rendering). Things may be a little rough around the edges for a while.
I’ve also defined the first post on the homepage (actually, come to think of it, on any page) as an IE8-ready Web Slice – I’m not sure that this is really a good idea and I have some misgivings about Web Slices in general.