Dan,
The build is actually a vanilla version of SQL2k. You have to apply patches after installation to get it up to SP4, but they are included in the Service Packs Cisco issues for the UCCX software. The difference between the Cisco version and a regular Microsoft version has to do with some additional tasks that the installer does that are required for UCCX....so if you're considering doing it, the answer is no, a regular Microsoft SQL CD will not work to install or upgrade the SQL server even if you had the exact same version in your hands.
And be warned: If you're installing an HA system, do NOT install any patches onto the servers (OS, SQL, or CRS Software) until you have both servers up and operating in HA mode. If you start patching, there are some patches that will go on out of sequence with the install that will cause your install to fail.
Cliff