I suggest you contact the vendor to verify whether or not CentOS 5.1 and 5.2 and onwards are supported. I suspect if they support something as generic as "RHEL 5 ES" and they support CentOS 5.0 then they'll support all versions of CentOS 5.0. Since CentOS 5.2 is based off of RHEL ES 5.2.
In the past, Ensim used to be very strict on the OS version they support. I guess Parallels would not be more flexible, but you are right, I will double check... you never know !
If not, then I suggest starting a subscription of RHEL 5 ES, or pick another software vendor that'll support you, or support yourself. I don't recall having any issues getting support from VMWare for ESX running CentOS guest VMs.
nate
I dont expect issues at OS level (otherwise, I would go for RH), but Parallels products can be very touchy when it comes to interaction with OS.
Thanks