What's the INT to Spellpower conversion? Read on...

One thing that's been driving me crazy is the INT to spellpower conversion. I thought it was give or take 1 to 1. Close.

Druid: Balance PvE (updated for Cataclysm release) - Elitist Jerks:

Intellect:
Intellect provides 1 spellpower and 0.00154% to crit per point. With Mark of the Wild, Heart of the Wild, and Astral Leather Specialization, it provides 1.169 spellpower and 0.0018% crit (555 points per 1% crit, a bit under 1/3 of a crit rating).
Similarly, with these talents, one point of Intellect increases your maximum mana by 17.53, and your regen from Replenishment, Euphoria, and Innervate correspondingly.
These things together make Int the best stat for both DPS and mana.

Spellpower:
Intellect, without the talent bonuses, crit bonus, or mana gains. Basically a weaker form of Intellect that only appears on weapons and trinkets, but is still good.