Ram Timing

What is ram timinglike for example 3-5-5-7 ? I have a total of 512 ram. Well to be exact 2X256 Pc-2700 2.5-3-3-7. Like if I wanted to buy this ram http://www.newegg.com/app/ViewProductDesc.asp?description=20-141-433&depa=1 Would the ram timing matter to be compatiable with the ram i already have so I can get a gig of ram?

 

These timings
The first number is the burst mode cycle to get the first 64 mb of ram which is (3 cycles) the second third and forth are to get the next 64 mb of memory and so on so 3-5-5-7 means it will take 20 cycles to get the whole 256 of memory 3+5+5+7 = 20
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oops forgot to mention
the description of the memory doesn't give any indication of the burst mode
(1st cycle) and other cycles times and to be fair i dont think you would notice a major diffrence if it was more than 5 cycles slower if you go to
http://www.crucial.com

they have a section to find compatible memory for your mobo.