Whilst I prefer having Windows users completely switch to Linux (or a Mac for that matter) instead of running Linux as a secondary OS or using an emulator to run it, some users simply need to be slowly weaned out of their comfort zone, even if that zone is in chaos. :) The best way is to slowly introduce Linux.
distributions have come a long way and it is now easy to reboot your Windows machine, insert the Linux LiveCD and play with the new OS… until you get used to it and dump Windows. Unfortunately, despite the full features of the LiveCDs, CDs are still cumbersome, i.e., it either gets lost or gets scratched.
In comes WUBI, a no-CD required Linux installation for Windows users. Now, if only all Windows users check out WUBI, then I think we will all be happy. Whilst it should be pretty straightforward to use, just be aware that it is still beta. :)