A small succes story:
My parents are pretty computer il-literate. My dad uses his computer quite often and has some understanding of what he's doing and manages to do a few different kinds of tasks. My mum has no clue at all and doesn't want to know either. She's learned how to use an auction site and she knows how to use email but they're 'tricks', performed without understanding what she's doing.
On my dad's PC with Windows XP, he's had a couple of weird problems lately when booting: his BIOS accused him of making mistakes when overclocking. My dad doesn't know what overclocking is, or a BIOS for that matter. None of these problems were bad enough to take more than a single key-stroke to fix until all on a sudden the computer refused to boot into Windows all together. Windows would load, BSOD and the machine would try to boot again.
It's uncertain what caused this. It may have something to do with my mum shutting down the computer via the start menu, making sure the computer was off by pressing the on button and then pressing the on button again, immediately.
My dad took his pc away for repairs. Then he rememberred I have a spare P4 laying around, which he could borrow of course.
I made a fresh install of Pardus for him. He's quite a different user than I am: he uses local mail, has a printer, uses office software. So, I'm new to most of the technology involved and it took a bit of fiddling to get it all working,
but I got it all working. KMail replaces Outlook, his printer / scanner works and sofar most (not all) of his documents appeared nicely in OOo. I failed to get his VPN program working: there's a Linux client but we've no documentation of how to connect (other than 'install Citrix client for Windows by running custom script, accept license, call helpdesk when there's a problem'. Helpdesk borked on the mention of the name Linux.)
He gets his own PC back on wednesday, with Windows XP and MS Office re-installed. It's OK, he's seen the power of Free Software and once he's back on MS' turf I no longer have to function as helpdesk.

The story here is that I tried a Linux distribution on a sceptic and unwilling person and I've not been let down: it performed admirably and the test-victim hasn't been able to find a serious flaw with it, despite trying. He repeatedly called it "difficult" but every time I asked him to think about what he was doing or I made him do the same thing on his Windows laptop: nothing proved to be exceptionally difficult. That'll make him think the next time he takes a couple of hundred Euros to the shop for his OS or office suite.