How important is Quad core? (iMac)

[micahPRT]

So the new iMac has 2.5GHz quad-core i5, (I'm looking at the base model) and it is looking pretty sweet to me.

I could, however snatch up a refurb 3.2, i3, 21.5 for cheaper, or a 3.6, i5, 27 for a bit more.

What on earth is the best idea?

I am fairly dependent on Final Cut and Compressor on a regular basis... but would the 2.5 Ghz machine slow down the rest of my general computing?

Here are the refurbs...

http://store.apple.com/ca/product/FC509LL/A?mco=MTkwMjE3ODQ

http://store.apple.com/ca/product/G0JM0LL/A?mco=MTkwOTc0MTM

 

[Gold89]

For video editing you definitely want the Quad Core.