Hello and thanks! My version works ok with vista, and it's only the next one up. It might be worth asking Serif to see if it's compatible.
If it doesn't work you can find version 7 or 8 pretty cheaply. There's one here for £9.99
Amazon.co.uk: WebPlus 7 Home Page Creator: Software
Or you can download a trial of version 7 here:
Serif WebPlus 7 - vnunet.com
Regards
Martin