Need help quickly!!!

Hi, I'm having problems and i really need some help. I have a Abit Nf7 and today decided to update the bios. So I did that. and afterwards all booted up fine. So i was looking around the bios and decided to up my 2400+ to 166 x13. I save fine, but on the next power up it starts beeping like crazy high and low and everything so i shutdown, clear cmos and boot up again. All is cool so I try 150x14. That works and I can boot so I try 166x13 again. It beeps like mad again so I power off clear cmos and boot back up at stock settings. Now I can boot, but the system hangs at the windows xp welcome screen. What's wrong? I really need help quickly so anything would really be appreciated.

thanks,
Kent

You could always try a reformat. Other than that i dont know what

First make all memory timings the slowest.
Try 166 x 10 first to be sure the memory is not the porblem, then increase the multi 1 by 1.
Increse the mem timings 1 by 1.