Truvativ SS crank spider question

I recently purchased up a set of Truvativ SS cranks on Ebay that will require a spider. I don't have them yet, but can anyone tell me if I'll need a specific spider, or is something out there compatible. I had a look at Cambrias website, and the arms do seem a little less "concave/convex" depending on how you hold it ... flatter sounds better. I suppose that just allows the chainring to be installed on the back of the spider (properly?), whereas alot of us use a crank intended for three rings and have to place it in front of the spider for a better chain line.
Anyhow, I am starting to wander. Yea or nay on the spider? Thanks!