2 windows directories

I recently installed a K7s5a motherboard with 1300 AMD processor for upgrade of old computer. Swapped the old hard drive with windows xp to new computer. Upon startup the system came back with missing or corrupt “himem.sys”, “dblbuff.sys”, “ifshlp.sys” “cannot find win.com, unable to load windows. I would like to reinstall windows xp but there is no way to do it with out doing a clean installation. I tried to install win 98 and found out there are two windows directories. “c:\windows and c:\windows.ooo. What is the cause of swapping a hard drive from one computer to another and getting all of these errors?