Paul
I'm not particularly experienced and only recently went back into this.
I photographed Comet McNaught with Kodak EliteChrome 400ASA slide film. Had to go to the big shops to purchase and it took me a while to find a suburban photoshop who still processed slide. See this thread for pics:-
http://www.iceinspace.com.au/forum/s...ad.php?t=16990
Then more recently I went for widefield shots of the stars on a little tracker I set up. I didn't expect much so just pulled some Fuji 400ASA colour print film out of the fridge where it had been for a few years. Results were better than I had anticipated so I put them here:-
http://www.iceinspace.com.au/forum/showthread.php?t=19735
My suggestion is that you use no less than 400ASA film. Slide is reportedly the best choice. If you search the web - probably "astrophotography film", I'm sure you'll still find some historic sites that talk about film work and choice - I've read several some months ago. However, I suspect the days of hypersensitising film with reforming gas 
are now long gone! Try this site from 2004:-
http://www.covingtoninnovations.com/astro/films.html
However, I'm going digital as soon as I can afford to!
