Zotero is great
If you’re studying, or you have to write academic prose, you need a reference manager. Most universities (in Australia) have a site licence for Endnote which is OK, as far as these things go. I tell students that sucks, but it sucks less than managing your bibliography manually.
Zotero is, on the other hand awesome. It is free and open source, and it lives in Firefox. It can suck references down from most university library websites, from Google Scholar and from many other places where a student or researcher is likely to find material. It can remember where actual downloaded papers are and it can help in keeping notes on different references.
The thing that makes Zotero really worthwhile, though, is that, like Endnote, it integrates with MS Word (and OpenOffice, if you’re that way inclined.) Unlike Endnote, the integration is not annoying.
If you have to write academic prose, I’d strongly suggest that you give Zotero a try.