guslaw - don't be afraid to post in the blender forum, we don't bite ;)  There are also lots of tutorials on the blender3d.org website if you click on "tutorials and help" up at the top of the screen.

**How to convert .ply files with blender:
**(I haven't actually finished downloading the files in question yet, but the import/export works pretty much the same for file types)

1. Open blender ()
2. There will be a box in the middle of the screen.  It's highlighted around the edge in pink, that means it's selected.  Hit the 'x' key or the 'delete' key to get rid of it.  This isn't necessary, but it makes things easier.  A box will come up asking if you really want to do that, just hit enter.
3. Go to file-->import-->stanford PLY.  This will open up a window where you will navigate to where the file is on your hard drive, select the file, and hit the import PLY button in the upper right.  I'm assuming you can figure this window out, but if not just ask--it can be a little quirky, but I've gotten used to it and can't remember what needs clarification.
4. The model should import into the scene when you push the import button, and you should see it in the middle as a pink (selected) object.  This may take a while depending on the size of the mesh.
5. If the mesh was not selected (i.e., not pink), hit the z key so it draws the wireframe only (this allows you to select all objects, not just the front ones), then hit the b key and draw a "box" around the object with your mouse to select it.
6. Go to file-->export-->wavefront obj.  You will get a similar file browser window as before.  Navigate to the place on your hard drive where you want to save it, then in the second line in the window type in something like filename.obj.  The .obj part is very important, don't leave it out.