Interesting, apparently AMD64 owners are advised to
stay away from SP2 altogether.
I've have
zero problems even though I have DEP running for everything, apart from the mild annoyance of the Sec Centre telling me I have no software firewall every time I start up.
I'm quite happy with SP2, even if the only useful features are the DEP and the Sec Centre warning me when AVG needs to be updated - fair play that's some clever programming they've got going on there.