Judas mentioned my own personal preference re: email: I really, really prefer to use online email whether it's Hotmail, Yahoo, or Gmail. In fact, I'm using them ALL for various and asundry reasons. LOL!
My own ISP is Comcast and I hardly ever check the email there. I think the last time I checked it, I had 2 - 3 emails waiting for me. So, I just really don't use my own ISP's email much at all.
I'm using OE for other reasons. BUT, again, like Judas said, if my hard drive crashes, or, if I do a Windows installation without backing up my emails, it's gone. So, backing up or transfering emails to more permanent storage is a must.
The main reason I quit using Outlook 2000 itself is due to it generating an error each time I would exit it. Microsoft's KB says it's a problem that can't be fixed and that I need to upgrade to 2003 or better. I'm not interested in going that route as I really don't need any of the newer features of the newer suites....at least not yet. I'll likely wait to do any upgrading of Office until I finally migrate to VISTA....which could be a while.
And, although many people disparage McAfee, I've used it for years and it comes with Comcast for free. I'm used to it and don't seem to have any serious issues related to it. I MUCH prefer it to anything with "Norton" in the name.
But, Tipstaff, see if your clients can get by with OE instead of Outlook. Might be the remedy they're looking for.
Good luck!