No difference between flate rate and regular priority other than you can load up a flate rate box to some crazy weight and it still only costs $9

I ship live aquarium stuff flate rate all the time and never have any problems, it is almost always cheaper than shipping regular priority when you go over a pound or two.

Finaly got my new brass tops and my RMA'ed 7800GT upgraded to 7900GS back from Nvidia so at last I will be able to turn my PC on now while waiting to install the GTS.