Your desktop is old and the upgrade options is very very very limited. Also the performance gain from upgrade is minimized due to other outdated parts bottle-necking it. With $500 budget, you can get a new build. Go to the system forum in this site and read up some of the budget build. Also post a thread asking for help and advice on the new build. Send me a private message once you read up some of the build and start a thread there, I will be there.