Back on 11-29-04 you posted a thread on RAM upgrades and the first answer was:
I would be very hesitant to purchase a 512Mb RAM module for that system. The model number you quoted is the motherboard id, by the way, and the motherboard was manufactured for use in some HP and Dell systems, rather than for retail. I can't be sure of the situation for your board, as Asus do not provide support information for it, but quite a few similar boards of that era had limits on the RAM module size they would accept.
What that means is that the motherboard is OEM equipment made just for whom ever Mfr'd your PC. That's why the web site does not list any info. Further down in that thread, I mentioned that I had looked at the spec's for the ASUS CUW and CUW-B models (yours would fall in between these two) and the spec's were the same regarding the RAM problem.
So, one would assume that the spec's for either (I'd take the CUW to be safe) will be the same or very, very close to yours.