Given the sample size of the software for N900 it's unlikely for anyone to ever get a virus. Though it's possible that something that targets Debian could be adjusted accordingly.

However, it would have to be "download and install" and it would need to be on -likely- this forum, since no virus is complete if it attacks ONE machine. Once here, people would likely complain and the package would fail.

The reason why Windows has such a problem has nothing to do with community or support - it's pretty much impossible to get through these days. Ten years ago, on home OSs, maybe.

What Windows has is the average userbase and the sheer size of it. As a Windows admin I've seen my share of viruses and in all cases there's some user looking at the floor muttering something about "I installed this and that".

I don't even think there's such a a thing as a virus any more - last I've seen is CIH. Nowadays they're all trojans.

Make no mistake, if a billion people would have N900 and the right to install-from-anywhere, there'd be a million of the little buggers. For now, however, stick to repositories. Even better, stick with official ones. I'm guessing that the push to Extras gets someone to at least skim the code.