which ati graphics do u already have?
i say...go for AMD Athlon II X3 435 @ 3.5k and Gigabyte GA-MA78LM-S2 @ 2.5k.
but i will strongly suggest making ur budget 10k...and go for AMD athlon II X3 435, gigabye 880GM-ud2h motherboard and 2GB DDR3 1333mhz RAM. perfect upgrade.