I own the first one, and it has helped me a lot when I first started experimenting with lucid dreams. I believe everything covered in the book is basically on this forum, appart from the research studies and such.
Overall, I'd recommend buying the first one you linked. I still read the book sometimes :)
I think it is worth buying. It is a great book. If have done lots of online research already, you probably know all the information explained in the book. I doubt you will find something new. Still, there is something nice about having all that information bound into something you can hold in your hands, read during a WBTB, or give to a friend to borrow. Maybe I'm old fashioned, but I like books.
I think the two versions are just different printings of the same book. I've owned around 10 copies of the first one. I keep giving it away. I've seen the second one around, but never read it. I wonder if they updated anything?
All of Dr. Stephen Laberge material is top of the line. ETWOLD is the the basic bible for all modern Lucid dreamer. I think they are the same book, is just that one is a latest edition (re editing). I do recommend it.
cheers
Another vote for your first choice. I've got the book right here and am going to go back through it tonight for some relaxation techniques. Great dream experiences in that one as well.
I'm pretty sure they are just different printings, same content. Definitely buy one of them though!