There is a portable version of CS3 available? Well, that's new to me
I'm pretty sure that I commented the first one already in the rate avi/siggy-game... anyways, it ALMOST looks nice, the background with its black holes pulls the rating down...
Second one: Let me guess, how you cut out Dennis's face... Magic Wand tool to select the background, then invert the selection to have his face. I see that the black border of his face doesn't look as smooth as it should look like. Tip: the feather tool is a nice invention
Third: It seems that you messed around with the contrast-thingy. It looks good except on Luis's chest, there are some odd-colored lines. Try to remove them either with the Spot healing or with the Smudge tool. The background looks simple and neat =)
Fourth: Good ol' Justin... the background caught my eyes on that one, it looks really cool. However, you didn't do the desaturation perfectly if you look close enough, you'll see a light orange border running straight across Justin's forehead and hair. Speaking about hair, I found some bright pixels in his hair (probably from the grey background the original face was on). Try to darken or smudge them out.
Nnot that I try to talk bad about your work, I just give you ideas/methods/hints on how to improve them
edit: uh, post #300 =D