DDR stands for Double Date Rate and that means it doubles the bandwidth of the memory by transferring data twice as fast on both the rising and falling of the clock cycle. 

CAS stands for Column Access Select or Column Access Strobe and that essentially means the number of cycles for the memory to get information and then process that information. Also keep in mind that a lower CAS is much better then higher CAS. So try and keep CAS as low as possible when overclocking. 

This memory is also Dual Channel which means better overall memory bandwidth resulting in superior performance. In order to benefit from this technology you will need to have a dual channel motherboard. Non-dual channel motherboards do not have two fully independent 64-bit memory controllers, but dual channel boards do which means they have a 128-bit memory interface. Now they can be installed singly but obviously performance will be much less at the same MHz.

Details Specifications:
Speed: XMS4000 (PC4000) or DDR500 (250MHz)
Size: 1024x2 = 2048MB kit
Configuration: 64MB x 8
Chips: Samsung UCCC IC
Latency: 3-4-4-8 1T
Package Type: 184 DIMM
Heat Spreader: Platinum
Voltage: 2.75