Memory upgrade advice

[alexisonfire]

Wondering what would be the disadvantages, if any, upgrading from 2 x 512mb stick of corsair pc3200 XMS platinum to some low end 2 x 1gb sticks of geil pc3200 value ram?

Lets say i could sell my current ram for around the £50-60 mark, meaning the the geil would cost me about £60-70.

OR

Hopefully find another 2 sticks of 512mb cosair xms platinum for £50-60, and run 4 x 512? In your opinion what would be the best upgrade?

I heard the ultra-d doesn't like quad sticks being used?

thanks

EDIT: WILL NOT BE OVERCLOCKING

 

[alexisonfire]

Would some OCZ pc3200EL platinum rev2 ram run ok with my corsair?

Both have the same timings, and both are running at pc3200 speed. Only theres some things that are bothering me. I heard dfi boards can be temperamental using 4 sticks of the same ram, is 2 different sets not even worth trying?

Also will an x2 4400 support to different types of dual channel ram?