I came here fairly recently myself, but as far as modding FS, way back with '98 I got myself a copy of Abacus Flightdeck 1, and I just thought that was the coolest, at the time, I had no Idea that regular people could make planes for Flight sim.  I kept on buying those Abacus CDs practically every time I went to Fry's.  I found Simv, and all these other sites rather accidentally, one day I was just surfing GlobalSecurity.org ,yes you read right, and I followed a link to a site with a Downloadable Firefox, which linked to AVSIM, which I promptly got board with so I just googled FS addons and found Simv and that was only three years ago now, and now I can't stop!

Wow, that site looks old  ! I used Simviation since FS2002 and it looks much different now, and in 2002 compared to 98.