DIYbanter - Radiant Barrier Help

Here's the setup...

We have a very small room next to our garage - the 'Little Office'.
Two walls are outside walls, the third wall is partioned off from our
laundry room with framing and drywall, the fourth wall has a door that
opens into the garage and has walls (not sure what's behind the
paneling). The ceiling is a "drop ceiling". From the garage I can use
a small step ladder and see over the room. There appears to be nothing
above the drop ceiling except attic space, rafters and the roof
decking. This open space continues down into the main attic and behind
me is all the attic of the garage area. I am in Eastern Pennsylvania
and right now outside it is 82 degrees. It is probably 75 degrees in
the small room and once the computer and monitor are turned on add
another 5+ degrees, so needless to say, it too warm to work and it's
only April.

I was thinking of putting a vapor barrier in the open space above the
drop ceiling, laying out a roll of Fiberglass insulation and then
stapling sheets of radiant barrier to the rafters above the small room.

Would adding the radiant barrier from top to bottom to just that
portion of the roof (and probably extending it eight feet or so into
the garage) provide me any relief from the heat?

In order for radiant barrier to be effective do I need to do the whole
area above the garage as well? and the area on the other side of the
room (the house attic)?

I need relief from the heat but I didn't want to have to do the whole
house!

Are there any other options that I am overlooking to eliminate heat
from this small room?

I've considered adding some sort of flexible extension tube from the
air conditioning duct to pump in some AC, or adding a strong fan in the
attic to blow some of the hot air out. There is no climate control in
this small room except for two vents that pass through to the laundry
room.

Any suggestions?