I have a nice B&W 400mhz G3 and am considering the benefits of getting one of those acclaimed PowerLogix 550mhz G4 Zif upgrades. How much of a difference will I see in common tasks? I do a lot of burning, mp3 encoding, AIFF recording and editing/croping/filtering/mixing, normal internet, Unreal Tournament

, some pedestrian photoshop/graphics converter work, lot of gaming

, DVD movies... typing? That is a pretty full list of what I do.
To improve my system, I have installed a 40gb 7200rpm WD Caviar disk, and 640mb PC 133 Ram. Would I be able to see the benefit of the upgrade? Please note that I don't plan on getting a new system for two years.
Or, should I wait to see what happens with the rumored 800mhz+??? upgrades.