command to know installed drivers
 

how can i know threw command prompt,what drivers are installed in my rhel 5.

you means linux kernel modules ? you can use lsmod command to see the list of loaded kernel module

i have used this but it is not showing description like wise in windows {intel corporation 82915g/gv/910gl integrated graphics controller}.
is their any command to get specification of each module to be load.

modinfo command to show the modules informations.

It should be the i915 module. Something like this-

List edited down to a single mdoule.