I think what you're looking for - with one exception - is Hiveminder.
I've been using it for a little over a year - the free version is good and the Pro version is (if I remember correctly) $30 / year. It supports:
Task dependencies - so if you can't do task B until A is done, it will (by default) hide task B.
Task priorities
Due dates
You can add comments to each task, describing where you are at as you go
The pro version supports up to 500 Mb of attachments

Other things I really like:
It is also collaborative, so others can assign you tasks (even over e-mail in the pro version)
It supports a "hide until" date - so you can ignore some tasks for a few days while you concentrate on others
Recurring tasks

The downside is that it is an online service, not a desktop app or locally hostable web application. Whether that is a deal-killer will depend on your needs and level of paranoia, but the pro version does allow everything to be done over ssl.

(Just a happy customer, btw - not affiliated in any way with the company)

Absolutely . . . but then we won't sure until we get a statistically significant sample of those. I'm trying hard to imagine how to put that in a grant.

In the same way that "real men" only program in assembly!

You can read the abstract of the article in the Annals of Neurology at http://www3.interscience.wiley.com/journal/122266379/abstract

I sincerely hope, for your sake, that she knows you have a cold!