Okay, here we go.

my monitor model is Samsung SyncMaster 931c with 75hz [75 is max in settings]
and 2ms refresh.

now what i want to know, what hz's actually do and what are they ?

my friend says that 75 is very bad and i should set 100 or smthn , but it wont allow me to set 100 only if i open the closed setting which are NOT recommended ....

plz help me out :)