I've given up chasing the software solution and realised that a paper to do list (managed in a Filofax) is the optimal for me. Most of my tasks come my way through face to face discussion so there's no email to convert to a task etc. And if it can't be taken off the list this week then it's probably a project that needs diarying.

I do use Outlook for diary management but that's because I work in a corporate environment and trying to do anything else would be working against the system. But it's one calendar for everything (work and personal).