Yes, it only works in Firefox.
I do think Zotero is the superior software but then you can only use it in Firefox right?
I am using one of the latest versions of EndNote and it allows you to do Pubmed searches WITHIN the software, and drag your results straight into your customised folders. Since I still prefer reading papers from hard copies, I print out the papers and alphabetically sort them according to topics.
This is a little drawback as I use Opera as my browser, usualy I find what I'm looking for and then copy the address to Firefox. But you would need to have opened another program anyway, I need real browser for more advanced tasks than only searching in Pubmed.