Dell OptiplexGX280

​I need some honest opinions. I just recieved a Optiplex GX280 minitower P4 @ 3.4ghz, and I'm thinking about upgrading the PSU (500w PC Power & Cooling Dell cert.), RAM (4GB - PC5300), and VIdeo card (Nvidia GTS250 -1GB). Would this make a solid gaming PC? I would like to play FSX, LOMAC, and GTR2 with solid FPS on a 22" LCD. ​