On graphics settings page it shows how much Vram you will use at current settings versus available Vram.
As you change settings it shows you what affect it will have on V Ram usage. The big Vram eaters are view distance and texture settings.
I use a view distance of 42 at a res of 1680x1025 with a traffic density of 70. The rest is maxed out....
Runs at 25-50fps, lovely old job.
Q6600@ 3.3 and 4870x2 by the way.
I wouldn't be happy if I had a quad core 3.3 and the fastest gfx card on the planet and only got 25fps at low res. Even if it's only every now and again.
