I have bought an acer aspire E1-571 notebook. it came with windows 8 single language installed. but I have compatibility issues with a lot of my devices. I would like to install windows 7 on the shrunk partition I have created but with it being a GTP partition win 7 wont install. I want to keep windows 8 and run win 7 simultaneously. how do I do this without having to delete all the partitions ?