Well, hello there.. Luckystar!
First of all, you should never turn off CPU features (except for the ones that saves power: SpeedStep or EIST and some others i don't remember)
The other thing, let me do the math.
GPU: 21932/20944 = 1.0472, which translates into 4.72% more score in the GPU
CPU: 19045/18295 = 1.0409, which translates into 4.09% less score in the CPU (which i'm guessing is because you turned off all the features on the CPU)
Overall Score: 20894/20435 = 1.0224, which translates into 2.24% more score Overall.
Getting a 25k score would mean that you have to achieve with your overclock a 22.33% gain (in 3D Mark Vantage)
Which i'm pretty sure is impossible, because that way we'd all buy a GTX 460, bump it up to obtain a 22.33% difference (in 3D Mark Vantage, not the card clocks!) and theoretically you'd have a GTX 570? that doesn't make too much sense for me.
Can you tell me you OC numbers? (Before and after) i could come up with the math and numbers and give you an even better explanation.
EDIT: i just saw your CPU and did a little math. You OC'd your processor from 3.06GHz to 3.91GHz, that translates into 27.78% of OC! and even that way (turning off the CPU features) it gave you a loss of 4.09% in the 3D Mark Vantage score. let's say that you don't turn off the CPU features and instead of losing 4.09% in the scores, you gain 4.09% in the scores (taken the non-OC'd value).. your scores would be at: ~20600, that MEANS
that you only gained 4.09% in 3D Mark Vantage scores with a 22.78% of CPU OC..
Which means that for achieving 25000 scores (22.33% difference from your base score), you need to OC your processor 124.37%, which would be: 6865MHz or 6.86GHz.
this is just the theory and i'm not an OC'er.
i just happen to be good at maths.
Hope that my info helps, and i'll be waiting for the Video Card numbers for me to do the maths and to give you a "decent explanation of how high you'd have to OC your card to achieve the scores you want"