Thanks to all for your advice – I eventually went for the Canon 100mm which turned up yesterday (along with a shiny new 40D). I’ve run a couple of test shots, just to get a feel for the capabilities … I must say I am quite impressed, although, as you mention Thorsten, it may need a bit of practice on the DOF.
I’m looking forward to giving it a more thorough run-out soon…. Hopefully I’ll get a few shots up in the macro section.