Another Dually Question

I just read the prev posts.. I'm still confused..

I bought my used G4 500Mhz Dually and I'm thrilled with it but now I'm somewhat confused....

I want to purchase the new Myst Game "Revelation" when it comes out but minimum processor speed for the game is 667 mHz. I've been told that this game won't work on my dual 500mHz G4. Is this true?

I've been told that software not written for dual processors is not faster than a single processor. But everything on my dual 500 runs MUCH, MUCH, MUCH faster than on my PowerBook G4 400 (same amount of RAM).

I've been told that the system uses the 2nd processor to process graphics and that the apps have nothing to do with it.

Can someone help to clearify?

To really take benefit of Dual CPUs, the application has to be written especially for this. It will then split the tasks between the CPUs, which will of cours make it faster.
Mac OS X itself uses both CPUs, if it recognises a dual configuration. I never had the opportunity yet to compare a dual to a single, with the same CPU speed, so I can't tell if the difference is very significant.
Desktops are always faster than laptops, due to their construction and the fact that they don't have heating and power concerns, and therefor don't need to adjust the CPU speed so that the laptop uses less batery or to avoid overheating. Desktop CPUs run at full speed all the time.