Help me Guys..my new LG monitor doesnt display to its mentioned resolution...

I recently bought a LG 19 inches widescreen LCD monitor..the exact model name is L194WS...

Its mentioned on the carton and on the manual that the optimal resolution should be 1440 X 900.....but mine shows only 1280 X 720....@ 60 Hz,32 bit

I hv already installed the driver provided wd the monitor...

my system specs are...

-1 GB ram
-Intel P4 @ 2.8 Ghz
-Intel 865 gv chipset....maybe its 845 gv...

-onboard graphics memory...64 mb...


Thanksin advance