Hey raffaz nice to see you , not seen you for a week or 2
Also it realy depends on what type of ram you are running and what cpu you are running . If both are low performance then the card will be better IMO seeing as the onboard is sharing cpu and ram but if its decent cpu and ram like C2d and ddr2 800 then the onboard will prolly do fine .
One place where the card might come out on top though is higher resolutions cos it has its own dedicated memory to put stuff in whereas the on board has to scrounge off the rest of the system . Like raffaz said your best bet is to benchmark and see . Also you may notice in different games one may come out on top but in other games the other may come out on top so also try playing your games with each one and see what offers best for the games you want to play