Memory

Flame me if this is the wrong group!!!

I have a Gigabyte GA-K8N Pro - SLi motherboard with 2 x 512mb Crucial
Ballistix memory.

I want to upgrade to 2GB of memory, but instead of putting in 4x512, to
which i hear knocks the memory back to 333mhz i will be going to 2x1gb.
If this is the case then I am also considering changing memory manufacturer.

Would it be worth changing to these? or is there not much difference?

Corsair TwinX or TwinX Pro
Mushkin HP Blue Series

Cheers
SlicK