Doh! I didn't think of that... I missed the obvious! Thanks so much, it seems to be working now :)
One remaining question:
The filename is entered in the database, but I have set up the file upload wizard to put the files in a 'files' folder. Is there an option to put a relative link (files/myfile.doc)? There are several options in the wizard but I'm not sure what they do (Field Name, Temp Path, Simple File Name and so on). I've found the getting started documentation, is there a detailed guide?
Thanks, Jason, your help is much appreciated.