You don't have to buy a hole saw. I just use a kitchen knife and a pair of sheet metal snips. Trace the pot for the hole. Stab or slash with knife. Then cut out circle with tin snips. Easy.

As far as size of pot, it depends on big you plan on growing. Latewood is right to use a large pot if you're growing large plants. You will need the weight, otherwise the plants will tip over. You could tie them up. Weight wil definitely be a factor.
Gen Reviewed by Gen on . Someone tell me if this system is any good http://cgi.ebay.com/16-Pot-Pro-Hydroponics-System-Complete-FREE-SHIPPING_W0QQitemZ7745126976QQcategoryZ43555QQrdZ1QQcmdZViewItem Thats one i was thinking about getting.... This is another.... http://cgi.ebay.com/32-Pot-Pro-Hydroponics-System-Complete-FREE-SHIPPING_W0QQitemZ7745126983QQcategoryZ43555QQrdZ1QQcmdZViewItem I am probably going to order one of these two if they will work for my entire grow. I just REALLY need to know if they will sustain my plants in a SOG type grow. If Rating: 5