While I am not familiar with the ASRock board, I have my 3700+ stable overclocked to 2.8Ghz on an ASUS A8V-E Deluxe with an XP-120 heatsink.
I am using a CPU clock of 255 with the 11 multiplier.
My Vcore is set at 1.5625v
Using the 166 memory divider (DDR333)
The CPU-NB link (LDT) is linked to your CPU clock. The multiplier times the CPU clock should not exceed 1050. The safe bet would be to drop it to 800 (4x).
To explain the role of the memory divider, I'll walk through your settings: 250x10=2500.
Using the 166 memory divider, you are dividing the CPU multiplier by (5/6): 10/(5/6)=12.
Thus, for determining the memory speed, you are effectively dividing the 2500 by 12:
2500/12=208.33 or roughly DDR417.
Your only other concern would be if your memory (assuming native DDR400 sticks) can run at DDR417 with the stock DDR400 SPD settings.
As for BIOS resetting, not all do it the Abit way, so consult your motherboard manual.