Mark,
RFactors' web site is
www.rfactor.net.
The main purpose of rFactor is to give a basic program to act as a template to implement mods.
In general, once you pay for and download rFactor, you can download most of the mods for free. One of the best sites to download these mods is
www.rfactorcentral.com.
The only time that you may have to pay is if you join a league. Cybercupracing is $50.00 for the year, but the benefit is that CCR can turn people away and only have mature drivers that you can trust racing with you. In free leagues, you commonly get younger kids or those people that don't take it serious, which can be very aggrevating.
I love downloading the different mods and just goofing around, but I like league racing the most.
The 1979 F1 mod is really fun and can be downloaded at rfactorcentral.com. In addition, you can download almost any track and race anything on them. So if you wanted to race a Cup Car at Monza, you could.
Let me know if you have any more ?'s.
Mike