adhoc vs. access point (speed)

Hey,

Currently fairly happy running 2 pcs with 11mbps USB wifi cards in ad-hoc
mode. Unfortunately even with a "very good" connection I never get more
than 33% throughput (ok this is using windows task manager not sure how
accurate it is).
Would switching the main pc to using an access point, or even using an adsl
wireless router thingy improve this speed? Is there any other way of getting
more performance out of it (like with the old dialups, changing mtu/frame
sizes etc). I only need a little extra speed to be able to serve divx's to
the laptop and into the tv of the front room.

Cheers,
Chris