CONNECTING TWO PCS

Hi,  I want to connect two PCs where one is operating under WIN7-64 and the other is under WIN8 -64.  I want to maintain total functionalitiy on both machines.  However, the main use of the WIN7 PC will be as an extended storage device for the WIN8 PC.  What is currently the best way to accompl;ish this.  For example, should I network them with both connected to my router separately or connect one PC (which one) to my router and then connect the other PC to it using a cross-over cable, or how else.  All suggestions are welcome.
Thank you, Clarke