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 24/2.8, 50/1.7, 135/2.8, 70-210/4, 100-300 APO, 500/8
Sony 18-135mm SAM
Tamron 28-75/2.8, 90/2.8 Macro, 70-300/4-5.6 USD, 200-400/5.6