Dennison is a good brand, but you have to make sure you get the fine version. It has a finer needle and smaller tacks than the regular gun (I think it's the 1/4" tacks). I'm pretty sure this is the right one:
http://cgi.ebay.com/ws/eBayISAPI.dll...m=200375902421
Here's another website for it:
http://www.teppisonesupply.com/servlet/Detail?no=144