Heres something worth considering if you are a lvl 70 mage and want to get as much out of dmg as you can

http://img241.imageshack.us/img241/4113/magetriplepointlr0.jpg

I think those values are considered after you've speced into those particular trees... ie if you can get your stats up to 800 crit strike rating and +200 dmg after specing then that is the right spec for you. Of course i have a 30% chance to crit with my talents and my buffs and that puts me at 660 spell crit rating. This means that achieving the values presented in the diagram are not impossible.

What this graph does NOT give you is the value of spell hit. 1% spell hit is said to equate to +500 spell dmg. Thats how important it is. I have no spell hit without talents. If your fire and take the 3 points in frost that give you +3% spell hit, then you'd need 167 spell hit more to be able to take on an elete skull boss (lvl 73 elete).