Sorry, but Image Align was withdrawn from the market permanently at the end of last August. Toward the end they were selling it off for $39 instead of the normal price of $129.
If you already have a copy, or you can find someone who will give you one, you will find it makes distortion corrections very easy. And the older version works fine in CS3.
Yes, everything it does can be done using other tools, but I find it the simplest, most natural way to do those corrections. I'm very sorry it has gone away.
I think PTLens is what lots of other people use.