How Much Internet Bandwidth/Usage Does MY Mining Rig Use?
Bitcoin mining doesn't require much bandwidth at all!
It's worth noting that the higher the hash-rate of your rig, the more bandwidth it will require (as you will get through work units faster - downloading new ones and feeding back more frequently).
Seeing as though you are planning to use guiminer, you most likely won't use much bandwidth (most high-performance mining is now done with dedicated equipment as opposed to GPU/CPU mining).
If you're new to mining bitcoins, these sites might be of interest to you:
answered Oct 2 '15 at 15:42