recovery console mbr

I have to ask a dumb question, I will put my pride aside so I can get this fixed.
I have used winxp cd and booted into Recovery Console. I have tried fixmbr and nothing happens that I can see. Just comes back to the C:\WINDOWS> prompt. I am expecting some crunching of hd or spinning of CD. Have gone into help and it states that "fixmbr (device name)" is needed or if left blank then the boot device is used. What and where do I find the device name? Am I doing something else wrong?
I have done a chkdsk on hd and every thing comes up rosy. I have determined via forums that my mbr is corrupt and want to fix it.