Some responses to various comments above ...
"paid for software is usually better than the free stuff" - that is simply not the case. I suspect you haven't actually tried Free (capital F) software. PD software and Freeware is often a bit naff and unstable, tends not to get maintained for long after its initial release, and of course isn't very trustworthy, but Free (as in GNU GPL, freely redistributable, source-code included) software can be trusted and is often vastly superior to many paid-for packages. A few slick visuals and a thousand features nobody uses doesn't make up for MS Office's tendency to suck up malware like a sponge, generate massive document files that contain data you'd probably rather they didn't and cost enough to make the average home PC user gasp in horror.
MS Office has a lot more features than OpenOffice but if you're typing a letter, throwing a CV together or writing an essay for example OOo is perfectly adequate.
"most users don't have a clue what OpenOffice is, or where they'd get it from" - if most users can't figure out where to get OpenOffice.org from they deserve to buy Tesco's pish in my opinion, and it's no wonder they can't figure out the GIMP. You'd have to have a room temperature IQ not to try http://www.openoffice.org/ ...
Of course it's true to say that "day to day interoperability with MS Office is not seamless" (of OpenOffice) - but I suspect the same is true of Tesco's shrink wrapped stool samples. After all MS Office uses closed, proprietary file formats which are deliberately obscure. Interoperability with MS Office is not really very important.
And to the anonymous coward who opined: "Open office is crap" - in what sense? What is actually "crap" about it? I guess the fact that by your own admission you think in block capitals might actually answer that question though. Also, the fact that you think the GNU Image Manipulation Program is known as "the gimps" and are of the opinion that it is also "crap" is revealing. Oh - hold on, careful, hold your head straight, I think you're drooling on your keyboard...
Simon B: I get your point about the absence of a well-rounded package with instructions etc., but I suspect that most people don't really read the instructions - just pop the disc in and wait for a Wizard, then "Next" their way through to "Finish". That actually works with the Win32 binary distribution of OOo. So the only real hurdle is pointing naive users in the right direction for the download.
Re: "Financial" - try GnuCash. It is possible (though not perfect or particularly easy yet) to import Quicken data into it and it's a vastly superior accounting app - see http://www.gnucash.org/ - specifically http://www.gnucash.org/docs/v1.6/C/t3948.html for some documentation relating to importing QIF files. The documentation and the process it describes are a little involved and suit someone at least a bit technical with some experience on Unix-like systems but hey, this is the Reg, shouldn't be a problem there eh?