I have a Macbook Pro and have windows 7 running in Boot Camp. I would like to buy an external hard drive to back up both..Is this possible with one external hard drive or will I need two, one for Mac and one for Windows? I bought an Iomega Go this weekend that has the firewire connection, but I can only run it in Mac and for it to be acknowledged by windows, it says I need to reformat it (the iomega). Help . Thanks.