how to configure grub for dual booting?
 

we have 2 hard disk redhat 7.3 and winxppro
OS is already installed, how to make it dual boot using grub??

a simple search on this forum should get you your answer
But here it is anyway:
Did you install grub during RH install? If so where? If in the mbr then it should be working nicely if in a boot partition for linux then you should point the windows boot loader to where Grub is (plenty of info on that here too)
If grub not installed install it (in my opinion easiest done by newbies using the install cd's and upgrade, but you can also install the rpm and follow the manual)

Anne