Laptop SODIMM, 667 at CAS 5 or 533 at CAS 4????

I was going to upgrade my laptop memory (Dell e1505 w/Intel Core Duo 1.6ghz/1 gb 533mhz DDR2/ATI x1400 GPU (some shared memory)/100 gig HD.).
I was wondering if it's better to use the CAS 4 533mhz stuff or the CAS 5 667mhz? I have a link below of the ones that I'm looking at. They are all at the same price and I'm not sure which would be faster for me. I do light gaming with this laptop, so I don't know if this really matters.

http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=2010260381%201052910525%201309121117&bop=And&CompareItemList=N82E16820134555%2CN82E16820231118%2CN82E16820146517%2CN82E16820231116
 

orangegator

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What model processor is in it? Is it's fsb 667? If it is, then get the 667 CA5 ram. I recently swapped out 1gb of 533 CA4 ram for 1gb 667 CA5 ram in a friend's laptop and there was a couple percent increase in most of the Everest benchmarks. Not much, but it was there. But if your cpu only has a 533 fsb, then the ram will only run at 533 CA4 even with 667 CA5 installed.
 
By my invoice it's 667mhz :)
1 465-2379 Inspiron E1505, Intel Core Duo processor T2300 (2MB/1.66GHz/667MHz)
1 320-4651 15.4 Inch TrueLife Wide-screenWXGA, for Inspiron 6400/E1505
1 311-5776 1GB, DDR2, 533MHz 2 Dimm for Inspiron 6400/E1505
1 320-4655 256MB ATI MOBILITY RADEON X1400 HyperMemory, for Insiron 6400/E1505
1 341-3109 100GB 5400RPM SATA Hard Drive for Inspiron 6400/E1505
I also have XP MCE installed and have NO plans on installing VISTA on this system. I'll also be at the maximum allow memory size of 2 gb's! :)

So I'm betting that the 667mhz CAS 5 stuff would be the best buy for my system. If it gets me the best speed at this cost than that is what I'll go with.

Edit: I forgot to mention that the manual states that I can have 667mHz DDR2 installed, but I know this doesn't always mean that it'll run at that speed.
 

That is what I got. Just wanted to make sure that the 533mhz CAS 4 was going to be as fast as the 667mhz CAS 5 stuff.