performance wise - what is the difference between an integrated mobo with an AGP video card added and a non-integrated mobo with the same video card used? any web sites where this is studied and compared? Al

My understanding in that regard is that there should be no difference. Many gamers have bought MBs with onboard graphics, intending to install a card, in order to get the onboard periphials available. In the case of nForce2 chipset MBs I don't think anyone is building MBs that will run memory at 400 with onboard video enabled. This would of course impact total system performance.

Thanks an interesting question. The nforce2 igp northbridge (graphics) versus the nforce2 spp northbridge (non-graphics) is the only case I've seen studied. In that case the igp is held back quite a bit in terms of max fsb because of the on-chip graphics, and the heat caused by the graphics processing is the problem. Imagine combining the heat of your vid card gpu and your northbridge into one chip. Nvidia has stated that the igp northbridge will achieve 400fsb with the graphics disabled, and in most cases I've seen, having it enabled restricts you to maybe 370fsb. In the below link the guy turns graphics on then off, hitting 360-370fsb with it on and 450fsb with it off. Considering that he is using the revision 1 version of the nforce2 chipset (which hits a lower max fsb than the rev 2 that everyone sells now) and can hit 450fsb suggests to me that disabling the graphics does indeed put you on par with a non-graphics chipset. http://www.overclockers.com.au/article.php?id=147422