If I'm using a 256mb ddr video card. What should the Video Appature Size be set at in the bios. 256 or 128 for the best performance.

Craig

You've got 256mb ddr in your AGP card and thats a lot.
It won't really matter how much you set the AGP Aperature Size as far as the performance is concerned. You may want to choose the highest setting available in the bios but since you've got lot of ram in the AGP card you don't need to do it. I don't think any application/games will require more texture memory since 256 megs of video ram will be more than enough.
How much system RAM have you got?
Try not to set the AGP Aperature size more than half of the system RAM. Again, this one also doesn't matter becuz your system ram is not going to be used for texture memory compensation. 256 megs of video ram is just more than enough.

Set it to 128, its OK.
Set it to 256, it won't harm.

The definitive BIOS Optimization Guide (http://www.adriansrojakpot.com/Speed_Demonz/New_BIOS_Guide/AGP_Aperture_Size.htm) has some good info, abd a lot better explanation of what the AGP aperture does than I can offer, even having just read it. Recommended is 64-128MB Aperture. Keep in mind the "formula" posted to figure your aperture size was related to older cards, nowhere in the article is more than 32MB mentioned. With newer cards, tons of onboard RAM and usually DDR, the aperture is probably almost never used anyway.

Having 256MB on your video card, I would say go with 64MB, it probably won't need that much. I set mine at 64MB, using a 1GHz Celeron, 256MB RAM, 64MB DDR ATi Radeon 7000 dual output. Return to Castle Wolfenstein is the toughest game I have and it runs without any problems at all. No momentary freezes, no slow or jerky movement, no trails, highest detail setting. Ditto for AMD 950, gforce MX 400, also 64MB DDR.