Even if your server is a Windows server 2008R2 which is supported for the majority of McAfee products, but as soon as you have client machines running with XP and Vista, this combination is not longer supported. Be aware of that before making any decision.
Issues related to install, uninstall, connecting to or from are the most common.
The NAP platform requires NAP infrastructure servers running Windows Server 2008 or later and NAP clients running Windows XP with Service Pack 3 (SP3), Windows Vista, or later operating systems. For specific information about which operating systems support a particular programming element, refer to the Requirements sections of the NAP APIs in the NAP Reference documentation.