Post by Keeko
The thing with Disc is that it is currently a PvP/Support tree, and as such cannot stand on its own very well. If I remember correctly, I think Blizz we're planning on changing it for WotLK to make it more viable.
If you're not going PvP you have to either choose shadow or holy as your main tree and start building some points there. In your case, your main interests are dealing damage efficiently solo and in instances and possibly healing in instances. Speccing shadow will give you great performance in both areas. Slap on some healing gear and you will still be an OK healer, even if you have no talents that improve your healing abilities. The priest is a great healing class even in its basic form.
Dealing damage, on the other hand, can be trickier as a priest. Shadow, again do this superbly.
Staying holy and dpsing is harder. This is often reffered to the lolsmite specs. Smiting gets its juice from the Holy-tree. For a lvl 39, your talents could look like this: http://www.wowhead.com/?talent=bV0zZrxt0bbZx
Notice the low amount of talents in discipline. You could continue in disc and spec deeper there if you wish, but imo you would still be better off continuing the holy route, aiming for Spiritual Guidance and especially Surge of Light. Continuing disc will grant you more mana and better regeneration, but your dps will suffer until you reach the lower tiers of the tree, with Imp Divine Spirit, Force of Will and Power Infusion and even then do less damage than the holy route.
Smiting has the advantages of allowing you to be a better healer than the a shadow specced priest, giving you the freedom to heal whenever you wish. But, you wont do as much damage and possible be less group friendly, not having VE or VT anymore. The main concern of this type of priest is sustainability in terms of mana. You will be relying on Spirit Tap and a large spirit pool to keep your mana up, and thus you really need to actually get the killing blow if you're going instancing. However, you'd probably be better off healing in instances and leave the smiting for solo play.
So my advice if you want to go the easiest route is to just stay shadow and collect both dmg and healing gear for those times you are required to heal in instances. If you're more daring and want to try something different, give smiting a shot. Going full disc, however, is not something I recommend for levelling.
Post by Wildhorn
No in fact your lvling rate will go up because you wont have to drink as much as shadow.
But you will have to make sure to keep your Wand up to date. Mousover this : )
Yeah but cloth DPS gears usualy have stam/int/+dmg and praticaly no spirit.