Are you sure you had it backwards the first time? After I posted my reply I was getting kind of excited that maybe I understood it and went and googled it, and based on the pages I looked at, I thought I was understanding which means you had it right the first time. Either that or I'm just lost beyond belief.

Here is a couple of pages that I thought explained it reasonably well:
http://users.adelphia.net/~lubehawk/...!/inccodom.htm
http://www.cod.edu/people/faculty/fancher/Dominance.htm

Some tips (sort of modified from the first page with my own embellishments thrown in) that might help remember which is which:
Co-dominance: co meaning together, like in co-exist. You have a third phenotype, but it isn't really something new, just the 2 traits together, side by side, peacefully. Red & white hairs on a roan cow.
Incomplete dominance: one trait tries to dominate the other but doesn't succeed, so they get in a big fight and end up with both of their guts all smushed together and smeared on the pavement. You have a third phenotype, which is what results when those guts get picked back up off the pavement, where they got totally mixed together. Pink flower.


I also found this page, which is a sort of quiz about genetics.
http://gbn.glenbrook.k12.il.us/acade.../Genetics.html
I didn't go through the whole thing and at least one link was broken, but what I saw looked ok. It had a note on one page that is interesting: "Both incomplete dominance and codominance genetics problems work the same way. The only difference is in the way the cell cellular machinery works out the phenotypic expression." (their typo, not mine)

This is why we can get away with lumping everything together into co-dom (or we could call it incomplete dom, it wouldn't matter). The Punnett square works out the same, the only difference would be the appearance of each phenotype which we just memorize what to expect.