Which Upgrade?

I am debating on which upgrade would be for the best. Whether i should buy a 2gb 5870 which would be similar performance to my two 4870's but i could add another to it in about a month and it has dx11(500$). Or a phenom 965 two more 1tb hard drives (so i could use my existing one with them and have 3 in raid) and another 2 gigs of ddr3-1333 ram(480$). What i am mainly looking for here is which of these will yield the best results in games? But when considering the 5870 option remember that i can have them cross-fired in a month. My current system is as follows...

Antec 900 2 case
msi 790fx-gd70 mobo
amd x3 720( unlocked 4th core and have it 3.2ghz, tuniq tower)
6 gigs of ddr3 1333 ram
hec 1000 watt power supply (150 amps between 12 volt rails so i shouldn't have to worry about powering 2 5870's)
2 x 1gb 4870's (bios mod in which i couldn't raise voltages very much but gave me o.c. of 810 ad 1100)


Any feedback will be appreciated

edit: i will overclock the 965 as much as i can safely if that is what i end up getting