Your primary problem is very likely that your board doesn't autodetect (or have correct) settings for the CPU and/or the RAM.
As you say you have 256 MB of 2100 DDR ram I would suspect the CPU settings are the culprit. If you have two sticks, take out one and continue with only one.
You will find a jumper that CLEARS the CMOS table, believe me, there is one (could also be called CMOS discharge etc). Read the manual or go to the manufacturers site and download a copy if you don't have one. Use the jumper (ie switch off the computer, UNplug the power cord, clear the CMOS by shortcutting the jumper and revert) and see if your CPU is now detected correctly. ALso, if your BIOS has something like "Load fail safe defaults", use that option, that could also clear things up a bit. Do this after you have cleared the CMOS.
There is no software (I know of) that tells you the manufacturers rating of the components FSB speed, at least not in a easily interpreteable way. Waste of time to go down that path, with other words. The best (only sensible) way to find out is to READ whats printed on the CPU. The best possible software that you could use is Oda's WCPUID, but I'm not sure that it always identifies every CPU's values correctly if its running on false settings to start with and you don't have half of the data already. Anyhow, if you try this you have to find out how to read the different family & steppings values it gives you, and wether there is only one possibility for your particular CPU, assuming that you are really really sure which CPU you have. Then you still have to clear the CMOS, so just start with doing that right now !
Let us know how you progress, somebody is likely to come up with another possible solution once the settings are ruled out !
H.