A HD4670 will be a remarkable improvement. If you're even thinking of anything more, which would mean replacing the PSU, then you should probably consider an entirely new build. Even a low-end AMD build will run rings around your current system, and cost around $500.
well i live melborne aus so everything is slight more expensive than in the states (about $140-$170 for a 4850) so a 4670 is at least $120+
if i upgrade my psu how much wattage and stuff?
finding 533 ram is impossible ($60 order for 512 mb RIPOFF)
A 550W PSU is enough for any single graphics card, even the most powerful ones. If you're not going for the very high end, a quality 400W-450W PSU will be sufficient. Look for full range active PFC and 80+ certification. Antec, Corsair, PC Power & Cooling, Seasonic, and Enermax are among the quality brands.
oh *** forgot res and games.
res is 1280x1024 on 17"but want performance in the 20" -24" area
games sim2+3,cod4,5,6(MW2),c&c, warcraft, assassin's creed 1+2,starcraft 2 all the cool games