Unless it's changed since the late beta I've been running for a couple months the SP doesn't actually have an AV program included, it simply checks to see if one is currently installed and up to date. It doesn't get along well with Norton AV on my system but it has a love affair with the Panda. I know not how well it works with McAfee. If it continues to nag at you then just go to the control panel, open up security options...recommendations under Virus Protection and check the box "mind yer own biz"(or something like that) and it'll shut up about it.
The real conflicts with the service pack(at least for me) were with the included firewall and Norton Internet Security. They don't like each other much, but once again it's Panda bear to the rescue!
I've seen that too Kendan. Norton and Panda for instance fight like wildcats!