Budget rig

Coming from an AMD S939 X2 3800+ it’s time for a new rig. This will be a budget/bang for buck because I’m not a pro. I just want some more juice and lower latency across the board. My projects consist of Cubase 6, Toontrack Superior, IK Amplitube (several instances), around audio 20 tracks and about 10 midi tracks with VSTi and of course a couple of FX on aux busses, usually about 8. It’s not much, but I’d like to be able to still use a virtual amp real time in the last stage of the project.

I was thinking:
i5 3570K 3.4GHz
GigaByte GA-Z77X-UD3H
Corsair Dominator Platinum 16 GB, PC3-12800, 1600 MHz, 9, Non-ECC, Kit Of OR
Corsair Vengeance Red 8 GB, PC3-12800, 1600 MHz, 7, Non-ECC, Kit Of 2
525W PSU
3 HDDs (systemdrive may be replaced by an SSD sometime)

I 'm not sure on the amount of RAM 8 or 16GB. 8 would make it a lot cheaper. Also would I gain anything by moving to a CAS 7 latency instead of 9. How much difference would it make?

What do you say? Thanx in advance.