Is it really necessary? or just something nice?

I'm currently looking at purchasing either a 60" or 65" set, upgrading from my Optoma RD50...

the sets i have in mind are the...

of course... sony kds-a603000
and the mitsubishi 734 series 65"....

i sit about 9ft away... but really, is the 120hz deal a nonnegotiable issue? or just something extra?

my viewing material is xbox360, digital HD cable (lots of sports), and right now a SD-DVD don't have HDDVD yet... but do plan soon