As usual Wezlo has given an excellent response. For me the switch to Linux started as a money issue. Could I go to Linux and keep my older hardware (Dell PIII 600 384MB RAM) and not have all the upgrade costs in hardware and licenses from Win98 to XP or Longhorn on two machines (home and church)? Then when I realized that Adobe was abandoning PageMaker 7.0 and it probably would not run under the next Windows version (PM 6.5 won't run under XP), it became a compatibility issue. Finally when Dell, after 15 hours of phone calls, told me that the reason my computer wouldn't run was the Windows operating system, I decided to take the plunge. BTW, it ran fine on Linux.
It was a bit bumpy at first, but now with Mepis, Win4Lin ($68), and an old Win 98 license I can run BibleWorks, PageMaker, Theological Journal Library (Logos Libronix Library system) better than they ever ran under native Windows. If one does crash (very rarely) it does not take down my OS and other stuff like a word processor or mail or browser.
No Win upgrade fees, no problem with PageMaker or forced upgrade to InDesign, no more software fees (I just feel better about donating), better operability, friendly support, more security, and it is just plain fun... GOOD QUESTION, why would anybody want to go through hoops to achieve this?
Now I can save for a BW upgrade.