When a game has a G4 listed under the minimum requirnments (ie. UT2K3 has the minimum proccessor as the 733 MHZ G4 and America's Army is at 700 MHZ G4) does that mean that a G3 won't run it?
Depends. Judging from your sig you obviously have an 800Mhz G3. Those games should run; how well is another question entirely.
Might as well just download the demos and give them a try. For testing purposes, the demos are ideal. It'll let you see how well your iBook will perform.
To overly simplify things, isn't a G4 basically an altivec enhanced G3? If this were the case, then a faster G3 than the listed G4 should work. I imagine it's just because the G4 was the current standard processor, so that is what is used as a basis.
I wouldn't bet on it.
Games like nascar 2002/3 need a G4 processor. It just won't startup on a G3. Thus it needs Altivec. I think many other games need it too.
Usually the requirements would read: 700 MHz processor... meaning G3 or G4.
Apple posted the requirements for UT 2003 too: G4 @ 700 Mhz.
Edit: could also mean the necessity of a Level 3 cache!