Thanks for all the helpful (and very rapid!) replies.

But, embarrassed to say, I've made a typical newbie blunder - asking a question that's already had a very thorough thread addressed to it. I thought I'd browsed through most of the stuff on the SP forums, but I thought wrong! Typically, found this by accident mere hours after making the post. But my thanks none the less, and blessings be on your houses!

Now I just have to try and implement the solution............!

Cheers