The reason who most of us upgrade our PCs is (in the most of cases) the resources that a games needs for being playble.
The games companies spending a lot of money and hours in research and development to get their games more realistic and in order to manage it the resoyrces that needed from a pc getting bigger and bigger.And of course thats a good reason to make us spend money (to pay the hours of R & D 😉 ) at least one time per year to upgrade our machines.Thats life.
So my friend cacalala i think that the time for u to spend money has comes 😉 .I agriee with all the others about upgrade ur ram at least to 1gb and get a new graphic card at least with 128mb ram.