The thing to remember is that its going to be shared memory, and most IGP's memory access can be limited in quantity. That being said, the IGP doesn't care a bit when you are loading a large spreadsheet or what-not. This requires no shaders and generally won't even have a measurable impact on your CPU. If you are worried about it, set your IGP memory down to 128 MB.
Sony Zeiss 55/1.8
Minolta 100/2, 28-135/4-4.5, 17-35 D
Minolta MC 50/1.4, MD 35-70/3.5, 300/4.5