Great to hear your picking them up again am planning on lvling 5 myself ^^ (already got a highish priest)

btw just to give you an even better incentive it looks like WotLK will see the rise of deep frost for Raiding

With your group of 3 you should be able to sustain an insane critrate on single targets including Bosses (provided they don't change the talents).

This is the Basic Spec, with a further 20 points to spend wherever you like

Don't Rule out This spec, added AoE and Slowing but above all 30% refunds on your critical spell hits, which will be very often