Which RAM to choose? URGENT... reply fast

Hello,
I am looking to upgrade my system's memory. I currently have a 1GB DDR 2 6667mhz (PC2-5300) Ram. It CAS lateny is 5.0 clocks - i don't know what does these data mean?
I wish to upgrade it to 2 GB.
I got two Rams, tel me which one I should choose to get best compatiblity with previous RAM.
first ram is EVM 1 gb 667 mhz with 5-6-7-8-9-10-11 CAS Latency
and second Ram is Transcend jet ram 1 gb 667 mhz with 3, 4, 5 CAS Latency


Kindly tell me which one to choose - evm or transcend