If youre not clocking too heavily get
this where the tighter timings will help
Say what?
Cas 6 on those sticks is slower than a cas 5 kit.
Where are you getting tighter timings from?
Dont waste your time with cheap ass kits like that,while you can save a few quid on memory I wouldnt recommend you drop that low.
There isnt much choice these days with DDR3 becoming more commonplace now I know,but if I had to buy a kit now with a budget in mind I'd choose
http://www.overclockers.co.uk/showproduct.php?prodid=MY-039-KS&groupid=701&catid=8&subcat=817