Firstly, I am thinking of getting a second 6850 to crossfire it with my current HIS hd 6850. I only have a enermax naxn 600w PSU. Would it suffice? Also, my second PCIE slot is only x4. Would that cause any SIGNIFICANT performance drop? Secondly, I need to get a new hard drive. Would you all recommend me to get 2 separate hard drives, or just use a single terabyte caviar blue hard drive for my OS and games. Would that result in any performance drop?