For me the simple fact that I don't have to deal with viruses and antivirus updates, and the ability to load any file given or mailed to me without worries makes the decision of using Linux easy.
I've been using OCPN on Linux with very few problems since 3.0; used to have audio issues (not a critical issue in a
navigation program). The power management is fine, as is support for
AIS,
GPS, etc via USB. The system is rock solid.
As with any migration, going from XP to Linux will take some "getting used" to the slightly different ways. Not as much as going from XP to W8 :-)
I'm not up to speed on the bleeding edge of SDD, but normally they can only take about a million "write" operations before failure. Thus, I'd use them to store
charts, etc (read-only if possible) and put
logs and other active files in a regular disk (or even ram disk).
Ubuntu or Mint a good starting points for people not familiar with Linux. I prefer Debian, but is a little bit harder to administer.
--Diego