Hi Memetic,
You're good to go..
Off you go now to get SP2.
Just remember that SP2 includes a firewall that runs (IIRC) at startup, by default. I haven't seen how effective it is for myself, but it can't be any worse than the standard one. You may wish to disable it in preference to ZA, and that would be my choice from what I've seen. Perhaps those that have gotten a feel for it can offer more advice.
Cheers
Liam