fitting extra ram

[theredherringuk]

Hi all
1st post....bit of a newb!

i have Corsair CMX4GX3M2A1600C9 XMS3 4GB (2x2GB) DDR3 installed in my pc,

my question is do i buy the same ram as above to make 8GB or do would it be advisable to buy a better faster ram if so any suggestions.

Also installed
GIGABYTE Ultra Durable 3 series motherboard GA-H55M-UD2H installed
Geforce GTX480
intel cor tm i3cpu 530 @2.93GHz
windows 7 ultimate

The aim is to breath some new life into my old trusty rig.
thanks for your time and advice in advance.