I found this...enlightening.

"If using an AGP graphics card it is generally advised to set the AGP aperture to half the system RAM - i.e. set to 32MB with 64MB of RAM.  That said, with modern graphics cards with increasing amounts of memory, the role of the AGP aperture (which allows the card to share system memory for holding textures) is of decreasing importance. With modern graphics cards with 32MB or more of onboard memory you need not set the AGP aperture above 32MB (although you may need 64MB to complete the 3DMark benchmarks). Very large AGP apertures have been reported to decrease system performance."

Source

thanks for that info man.

Mine is at 256 with a ti4600 and 512megs ddr.
I did read that some systems may do better at 128 than 256 but I'm not messing with perfection. ;p

I hear ya. I have heard to set it at double the Video Cards onboard RAM, and set it to 1/2 the System RAM, but I've never really heard a good explanation as to why they say either.

Mine seems to work just fine at 64 and setting it to 128 or 256 made no difference and seems to be a waste. I have 384 system and 128 on the card.

I'd hazard a guess that the no more than 32Meg required comes from the assumption that all textures would be resident and geometry in AGP memory was unheard of. How old is that article?

They're refering to modern cards with 32 Megs or more, so I'd say not too old. Following their logic, it would be more true today with Video cards having 64 -128 Megs.