Welcome back, Joe.
First and foremost, if you're going to be flying mainly GA, please please please do yourself a huge favor and by your pick of the A2A Simulations products:
http://a2asimulations.com/ . They are the BEST GA products available for flight-sim. Period.
I still use FSX, and I have no big issues. Some people swear by P3D, though...
As for VATSIM, it's the same, more or less.
If you want to get into flight training on VATSIM to refresh your skills, check out VATSTAR.com.