As things stand right now, I am using FS9 pretty much as it comes out-of-the-box, with the addition of a few new gmax aircraft (non-AI). My question is this, if I am just using the default AI traffic, is there any real advantage to upgrading to some of the new AFCAD2 files available for default airports? Will it give more traffic? Will aircraft behave differently? Or will there be no difference at all? Thanks for your help.

I don't think you will have any advantage to do so... ...but let me tell you by not installing additional AI aircraft with real airlines and flight plans, just playing it Out-of-the-Box you are loosing a lot, however the beauty is in the eye of a beholder... all depends on your system etc maybe you are unable to use lot's of AI traffic maybe you just don't know, maybe you don't care if you don't care then don't bother installing AFCADS won't do nothing for you, but I myself would not look at MSFS without the volume of AI traffic that I have never mind all in real airlines liveries and no more of MSFS Airline Inc.You should try it out.Andy

Well, the reason I'm runing it out of the box is because I purchased UT right after the new patch came out. I set traffic to 75%, and have all sliders set at installation defaults and got about 4fps (hardly controllable) at places like KPHX, KLAX etc. This is with a P4 2.4, 51Mb RAM, GeForce FX5200, running Windows XP Home edition. I knew frames would drop but crap......with those kind of numbers I couldn't even fly it. So....I uninstalled everything and am back to a stock FS setup.

Whoah!I have exact same rig and everything on and getting 18-25fps.Tweak your linear filters, or take them out. That was my only problem, now everything smooooth!RonaldGlasgow

Okay, I'm a computer neophite.....please explain "tweak your linear setting". I'd love to have framerates like that!!!!!