sorry, we can't support Zotero 2.1/FF 3.6 anymore - there is just too much that has changed (as I sidenote, FF 3.6 is also not receiving any more security updates from mozilla, so you're exposing your computer to a constant security risk - people using outdated software is one of the primary reason for the spread of viruses).

You can download the latest version of the JSTOR translator (updates aren't pushed to 2.1 clients anymore, afaik) from here:
https://github.com/zotero/translators/raw/master/JSTOR.js
and place it in your ZOtero data folder:
http://www.zotero.org/support/zotero_data#locating_your_zotero_library
but if that doesn't help, we can't do much.

The problem is that the internet changes - in this case, the JSTOR site did (as do many others, we push an average of almost one translator update a day) so things _are_ broken and someone has to fix them. (Also, take the warnings about security risks seriously - just because you don't see how your system is broken doesn't mean potential attackers don't see it. And since you are using your computer on the internet, you're posing a security threat not just to yourself, but also to others.

The first link is a javascript program. Just download it (right-click (ctrl+click) on link --> save link as... and place the downloaded file - JSTOR.js - in the translator folder of the data directory, overwriting the existing one. No guarantees that will work, but I think in this case there is a fair chance that it will.

What open source means is that you're welcome to take the code and maintain a PowerPC compatible fork, not that the tiny staff of 1 1/2 and a ragtag group of volunteers (me included) has any moral responsibility to do so at the cost of neglecting other development. ("You" is a generic term here and needn't be you personally. It's possible that Zotero 3.0 would actually run on ten four fox: http://www.floodgap.com/software/tenfourfox/ e.g. - they claim it has the same code as FF 17).

While I don't think @adamsmith was "blaming" you personally for contributing to security risks, I do believe that each us has a personal responsibility to behave prudently even if it is inconvient to do so. When vulnerabilities are found in software that cannot simply be patched but which require a major rewrite, it may be not only impractical but impossible for the software developers to maintain backward compatibility. I offer another example. Consider vaccinations against childhood diseases. For some people, going unvaccinated is not a choice -- the very young or persons with serious health conditions for whom a vaccination can be deadly or as bad as getting the disease itself. The health and safety of those children depends upon "herd immunity". Their health depends upon not being exposed to the disease from children whose parents wrongly believe that vaccinations are dangerous. The greater the prevalence of vaccinated kids, the less risk for unvaccinated ones. Another childhood example: we now know that certain babycrib designs present a great risk of suffocation to the babies who use them. There are laws or regulations that block the manufacture and sale of dangerous cribs not only new ones but also in resale shops. The crib isn't worn out but it is defective by design.

While a computer may not wear out like a household appliance, it does become obsolete -- even dangerous -- because of hardware and software design flaws. Apple made a decision to implement major changes to its operating system and hardware. We can debate the fairness and reasonablness of the Apple decision. I do not think that Apple's decision should require other software developers to continue indefinately to support outdated Apple systems.

I think that it is reasonable to expect continued software support from developers who sell a maintainence contract. It is quite another thing in the case of free open access software. There will likely always be evil ones who find and exploit weaknesses in systems. Software developers must not only work to improve the features of their product, they must also continue to find ways to eliminate the continuing threat of malware. I agree with the Zotero decisions about the balance between, one one hand, progress and security and on the other hand continued compatible upgrades for older systems.

Yes, as Dan Stillman said, I was unlucky in purchasing a system that cannot be upgraded to Snow Leopard. I'm not sure, though, how I'm supposed to "accept" that.

Well, by "accept" I just mean understand that this is going to be the answer you're going to receive from us, given upstream decisions and our own limited resources.

But have you tried TenFourFox, as suggested by adamsmith? I would think it's exactly what you want. And while we can't really promise to help you with all problems you might encounter while using it, there's a decent chance things will just work normally.

But Standalone won't run on 10.5 as of Zotero 3.0.10 (because it's based on the same code as Firefox 17), and the bookmarklet and website aren't really what you want to be using for real work at this point. TenFourFox is the thing to try here.