That is a pretty old unit 2009/10 according to this review. You could put a GT630 in it but I am not sure that it is worth spending upwards of £60 for the gain that you will get. You will always be limited by the 2Gb of RAM and that is DDR2 and according to the spec cannot be increased. The processor is Socket 775 which was dropped some time ago. I would start saving for a new and more up to date PC if you want to play some of the modern games.
Sea of Thieves Review