simo: Tragic, but I agree with Chris. Why we use RISC OS is actually different to why 'most people' choose to use their Windows box, and IMHO this is why Linux hasn't penetrated the non-computer-savvy desktop world (and why Apple's market share is relatively small for that matter). Most people use Windows because of its market penetration - you can go down to your local 'Windows World' and buy stuff for it. It's not necessarily that they /like/ Windows, but that obvious disadvantage to the alternatives - the same reason most of us own a Windows box as well as a RISC OS machine. Marketing RISC OS to those people without knowing much about modern RISC OS is a hiding to nowhere. Hence, agreed, mailshots and blind adverts would probably fail.
Consider Chris's plan. You attract in the retrogamers, the 'tinkerers', the people who like to dabble with their machines rather than just run Word. These are people that actually just might see beneath the 'does it run Internet Exploder?' and look at the positives of the platform.