oh.. btw, its redhat 7.3 that i was trying to install.
i found a solution which is :
opening the grub.conf file you'll see a section starting with "title myLinuxDistro...."; after that, you have to insert a new one like this:
title myWinSystemName
rootnoverify (hd0,0)
chainloader +1
pay attention to the (hd0,0) section, you have to modify this according to the partition where Windoze is installed.
hd0 = hda
hd1= hdb
...
(hd0,0) = hda1
(hd0,1) = hda2
...
But how do i open grub.conf file in linux? all i see is dos in redhat, i cant get into gui...