Prime95 question: (Prime95 fails but 3DMark2003 doesn't)

I've been incrementally overclocking my 2700+ to see how far I can push it
and yet still be able to have it be stable in 3D games.

At certain OC settings, Prime95 will fail within 2 minutes, but 3DMark2003
doesn't (and I executed it several times).

How critical are the Prime95 errors, I mean, can they be ignored if other
benchmarks don't crash? I get one of those:
"Fatal Error: rounding was 0.499999 expected less than 0.4

The only CPU intensive tasks I'll be using this machine for are 3D games.

And if a 3D benchmark doesn't crash, but Prime95 shows an error, how stable
can I expect the system to be when I actually play games?
And if having Prime95 find an errors can be ignored, how long should I aim
to have Prime95 run before an error occurs if I still want to system to be
stable in games?
Is anybody running their system with Prime95 errors and not having it crash?
Why is Prime showing errors yet 3DMark2003 isn't crashing or showing video
artifacts?

I know, I'm asking a lot of questions here

Any of your input/experiences are much appreciated