Hey man I had this problem with the exact same setup. The problem is with the memory you're using they are probably PC2100 dimm's these are too slow for the overclocking. In this case you have to go into Jumper free configuration in the BIOS settings and force the memory to 266 MHz. Then set the overclocking to 175. If my memory serves me right. In any case you can play with the settings in the Jumper free config until the error message disapears. It worked like a charm on my system. All so make sure that you use only memory that is certified by ASUS on their page, I tried memory not posted there and all heck broke lose on my system.
http://www.asus.com/products/mb/sock...x/overview.htm
Also check the manual available from ASUS. You will see that when overclocking to an 800MHz CPU FSB, the system supports only DDR400 (PC3200) DIMMs due to chipset limitations.
The following FSB/DDR ratios are not supported by ASUS: 400/333, 400/400, 533/400.
These are the ones recommended by ASUS: 800/400, 533/333 or 266, 400/266.
The only work around I have seen is the one I suggested. In this case I slowed down the CPU FSB speed in order for the memroy to be able to comunicate on the bus.