Power Re Generator capacity questions

I am looking into purchasing a power re generator for my surround setup.  I have heard many reviews of its benefit in a system.  I do not understand the size of the unit I would need, wattage wise, to handle the system and not get over loaded from too much being put into it.  I suppose the biggest question is does the WPC of each amp translate into the total number needed for that particular component?  For instance, I have three large load components included in my system.  I have a 2 channel and a separate 3 channel amp - each one rated 200 WPC into 8 ohms as well as a 512 watt into 8 ohms powered sub.  The combination of those 3 components would appear to mean that I need a re generator that handles approx. 1500 watts for just those 3 pieces alone.  I would then have a universal player, plasma tv, set top box, tube pre amp and a small surround processor to add in after that.  Am I understanding this correctly?  Do I need to look for a unit that handles 2500 watts or so to cover all of my gear or are these wattage numbers from my gear the wrong numbers to calculate in the first place?  Any help would truly be appreciated.