It is likely that you do not have the proper graphics driver installed.
Ubuntu loads a plain vanilla graphics driver if it can't find one for your
card. In Linux most graphics drivers are open source and either reverse
engineered or are supplied by cooperative OEMs. Intel is notorious for being
slow while cooperative. The problem with 9.10 was that Ubuntu used a kernel
that relies on kernel mode setting and that caused some problems because
older drivers did not work, putting pressure on OEMs t produce drivers.
(Expect similar problems with 10.04 due later this month as Ubuntu has
switched to Plymouth to handle graphical boot. And this does not work well
with many existing drivers. Change can be exciting, but mostly it is a pain
until they get things down pat.)

Your best bet it to run Hardware Drivers in System, Administration. It will
tell you if there is a proprietary driver that will improve things. The
second possibility is that the graphics driver is in place but not
activated. You can do that from Hardware Drivers as well. If this does not
work then you can manually install a driver, but that is not usually
necessary.

If you ever want to find out about your hardware open a terminal and type
lshw (for list hardware). In your case scroll back through and look for
*-display section (use scroll bar). You can highlight and copy and paste
relevant section (not whole thing) as this is sometimes useful in
troubleshooting.