Hi Neil, thanks for getting back to me so quickly!
I see your point about the Module CSS, i did infact take out the reference from the .ascx file and all seemed to work as normal so that should solve it. There were a couple of other issues with the output and XHTML:
1. cellSpacing and cellPadding attributes shoule all be in lowercase.
2. the width, height and align values should be in quotes.
3. the img tag should close itself using />
I think that's it, hopefully this should make it XHTML compliant which would be very good.
Thanks again for your support.
Dan.