RAM suitability what do the ID tags mean?

The prefix KVR refers to their "Kingston Value Ram," a product line that is carried by many retail outlets and sells at an affordable price. Some might consider the KVR memory comparable to generic memory, because of the reduced cost of the components used, although Kingston gives their "KVR" memory a lifetime warranty. Kingston part number "KVR133X72C3/512" is a 512 MB PC-133 ECC DIMM, and ECC isn't compatible with Apple products. As for the prefix KTD, that refers to "Kingston Technology - Dell," which is system-specific memory for Dell products. In the case of "KTD-PE2400/512," that's a 512 MB PC-133 Registered DIMM, for the Dell Power Edge 2400 series. Needless to say, registered memory (like ECC) isn't compatible with Apple products.