search for the ms keygen elsewhere on this forum using the search button

then you need to look thro the registery for the serial that u used!
In win98 se using the command "regedit" typed at the run prompt under start menu you search for this key in the registery ...
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion
and the serial is on the right hand panel !
i assume it the same with win 2000 so edit it and replace it with the new key made with the kegen that you download from this forum