upgrade
 

I have installed redhat 7.2, on the PC of my friend.Since it does not
contain the video and graphical drivers, it directly boots into text
mode.
I have got a cd of Red Hat 9.0.I have come to know that 9.0 contains
the video and audio drivers for my friends PC.

My question is that is there any way, by which I can just install the
drivers of Redhat 9.0 on my friend's PC, and nothing else? or should I
have to upgrade the whole system to redhat 9.0?
If you have any doubts regarding the question pls inform me.
Any ideas on this matter will be welcome.
My friend had 845GL chipset. and sigmatelAC97 sound card.

You could install the drivers off the cd but they probably don't come in their own package but rather bundled with XFree86. I would suggest updating XFree86 for your starting point to get the video and such working... etc.