Is this a good build?

Looking at severely upgrading my current PC which is:

AMD Phenom II X4 960T @ 3.6Ghz,
Arctic Cooling Freezer 7 Pro rev.2
Asus M4A88TD-V EVO/USB3
16GB Corsair XMS3 DDR3-1600 RAM,
2x WD Caviar Black 1TB, 1TB seagate and a pair of 500GB Hard drives
Sapphire HD5850 Toxic 1GB
Corsair TX650 PSU
NZXT Phantom White full tower
Blu-Ray Rewriter
DVD-RW

Its not bad, but its starting to show its age.
my planned upgrade is:

Intel i7-2700k - Possibly cheap cooler or stock temporarily
Asus P8Z77-V PRO
16GB Corsair Ram (either vengeance LP or what i have)
Palit GTX 570 Sonic Platinum 1280MB

and the same HDD's, PSU, case and disc drives.

is this a good upgrade plan? and has anyone had any experience with these parts?

open to any advice or comments, and the more the better  
thanks!