OK, I don't understand this at all.
This is the BBC's RSS feed ( http://newsrss.bbc.co.uk/rss/newsonline_uk_edition/front_page/rss.xml)
If you view it in ie6 it appears to be styled with a custom stylesheet (nosol.xsl)
If you view it in firefox or ie7 the browser's default rss feed styling is used.
I tried to do something similar myself with this rss feed: http://www.bbusl.com/worksregion/4/rss.xml
It worked as planned on the Dev server. However, once I put it live onto our production server, the ie6 stylesheet is appearing when you view the rss feed in firefox !?!
How do I make it so the custom stylesheet only appears in ie6? What's the difference that's made it work like that on the dev server and not the live production server?