Sorry for my tardiness, been busy elsewhere.FSAA is Full Scene Anti Aliasing and is a software method of reducing the jagged lines representing straight lines at an angle on screen - it's particularly troublesome in sims like FS2002 where the runways, taxiways and aircraft parts have prominent straight lines to them and the effect can be quite distracting.
FSAA - or just plain anti-aliasing as it's more commonly known as there is more than one type - produces multiple passes of the textures and effectively blurs the edges of straight lines to give a smoother effect. Done right it's marvellous, done wrong it ruins the fps and makes everything look vague and indistinct. All modern cards offer some form of AA, but in different levels and flavours.
However, an easy option, often overlooked by the technophiles is simply to turn UP the screen resolution - the jaggies are virtually unnoticeable on an average monitor at 1600x1200.
Depending on card and system (and game) you may need to experiment with the different combinations of AA and Resolution as frame rates and results can vary. With most GeForce cards go for the highest res and the lowest level of FSAA, with newer ATi Radeons the AA is better turned up and the resolution lower.
Hope this helps.
Simon Evans