First off: Easier to reply if you don't make us link out to five different sites to find out what you're wanting to know.
Kingston ValueRAM 512MB 184-Pin DDR SDRAM Unbuffered DDR 400 (PC 3200) KVR400/512R vs. KVR400X64C3A/512
THese look to be the same part. The Kingston number is KVR400X64C3A/512, the first number is some made-up number.
Here is the Kingston compatibility chart for your Mobo:
There should be no problem mixing the Kingston and the Corsair.
If you install CAS Latency 3.0 RAM, your whole system will slow to CL 3.0 -- now you may or may not be actually running the Corsair at CL 2.5
If you want to preserve your latency advantage, you would have ot go with some different RAM that was CL 2.5