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.
Minolta 50/1.4, 80-200 HS APO G
Sony 18-135mm SAM, 35/1.8 SAM
Tamron Di 90mm/2.8