Thank you for your reply. But it has gone totally over my head

- u can make out I am not computer savvy!! so will appreciate your patience.
I tried saving in HTMLZ but when I try to open that file nothing happens. In windows 7 it keeps asking me if I want to open or save. I can resave it but I cannot open it.
I would love to use this feature as I have many ebooks in PDF and my ebook reader does not support this format of PDF, so I put them into doc or HTML first. Mobipocket Creator does that for me, but only one at a time, I need to convert in bulk which is where Calibre would help a lot, if only I knew how to do it correctly
Pls help
Many thanks