Basically, my question is this: Which is better/more important for a low level tree healer? Spirit or +healing?

I spotted Dalewind Trousers in the AH and snarfed'em up:

http://www.wowhead.com/?item=13008

Later, I picked up the Windscale Sarong in ST:

http://www.wowhead.com/?item=10842

Thing is, I'm not sure which is actually BETTER for me. I was stoked about the +25 spirit earlier on, but when I saw the +healing legs I instantly felt like those were better.

Any thoughts? I know that gear is gonna be upgraded and changed as I level so its not that big of a deal, but the underlying question will remain regardless of level. :)

I'd go for the Windscale just cause of the +healing

I heard rumors that Blizz was going to do something about Spirit? So I don't have to DE all the "of the Whale" gear anymore?

Well, spirit and int work together for mana regeneration for druids and priests now. The end result is that having more of both increases your regen by a nice amount.