Gpu and board compatablity

[vinutv]

i have a machine

intel I3 ,
intel 55TC MOTHER BOARD
4gb ram
1tb HDD

i have a serious issuue with my GPU nvidia 8400gs 512mb
its working perfectily

but when i checking the system rating in windows 8
with graphics card its 3.9 or 3.3
with out 4.8 and 4.9
i can play well NFS most-wanted 2 WITHOUT GPU .. but when i use it game become lagging ??

how can i solve this ,.,????
how to trouble shoot this ???

 

[Sunius]

Get a more powerful card? 8400 GS is extremely weak card.

 

[vinutv]

cud u pls select me a card which is not much costly