Dell PE 2600

I have Dell PE 2600 with RAID 1 configuration. it loaded with windows 2003 server and working fine. Now I add additional Hard drive which I pull out from other PE2600 (it installed with windows xp and some data file which I am interesting copy to my machine).The problem is Device manager can detect 3rd HD, but not from windows. Do I need do something to let me recognize this HD from windows?