Yeah in OBS there should be an option to use your video card. If it's not there then your video card is too old.
If hes just recording a webcam video and mic you dont need much. But if your gaming and recording its alot harder on the machine.
That elgato device may not be compatible with such an old machine. But hard to say.
RE: Elgato Opened a Can of Worms ~ It May Be Time To finally upgrade the PC