C: (or whatever drive it's in)-->ProgramData-->Adobe-->Photoshop Elements 5-->5.0-->Photo Creations-->special effects
I know there's a program that will install actions for you, but I don't recall the name of it.
I've got PSE5 and Vista, and I have fits with actions. I have all of my Atomic Cupcake PSE actions installed, but only 2 or 3 of them show up...this happened to me when I first installed, and then boom! 3 or 4 months later they were all there. After having to reformat and reload everything again, they are back to being mysteriously absent. I never had a problem with PSE on my XP desktop...but my Vista laptop does NOT like PSE 5.