Well, 175 and 25Mhz might be too slow, but 233 and 50 Mhz are fast enough to play any game.
I have to disagree here, even 603p@266 + 060@64 + BVisionPPC@97 MHz is too slow for any reasonable use.
320x240 lowres, skip 10 frames ...
That gives 5 fps update speed. I wouldn't call that "fun".
But I guess this is a matter of opinion.