Well... Having played all those games on a 500 ibook, they all run pretty good, except for AvP, it seems, no matter what detail I put it at, would run poorly. People with 300mhz iMacs were playing it, but not iBook users. I gave up on it. Maybe it will work on yours though. 4X4 ran well after a few seconds of caching, and driver will work decently with the details down.
Your 400mhz titanium will be slower than my 500mhz iBook was, the G4 is just a G3 with altivec and few other changes, that is, unless you're photoshopping, but that's it. So expect a bit lower performance on yours.
Oh, and about that error, go to extensions manager, and make sure that you disable all the crap NVIDIA extensions, ALL of them. God knows why apple put them there, but they were there on the older TiBooks and everone had to disable them.