A litle help please

[FrostedNipple]

I have

http://www.overclockers.co.uk/showproduct.php?prodid=MY-112-CS&groupid=701&catid=8&subcat=
Corsair 1GB DDR2 XMS2-6400C5 TwinX

I want another 2gigs

my current ram is clocked at 4-4-4-12

should i get

http://www.overclockers.co.uk/showproduct.php?prodid=MY-092-CS&groupid=701&catid=8&subcat=
Corsair 2GB DDR2 XMS2-6400C5 TwinX

i dont mind downclocking the other ram if this 2 gig set isnt up to scratch

i just want to verify compatibility, also other 2gig stiks that are cheaper and also compatible would be prefered, thanks in advance

FN