good travel books on backpacking across Europe on Eurorail.?

My fiancee and I are backpacking next summer across Europe for 2 months. We would like to purchase some good travel guides. any good ones? ones to stay away from?
We have never come close to doing anything like this so we need lots of help.

you should check out this site, I bought a book about the InterRail tickets and travelling across Europe last year

http://www.trip-extras.com/bookstore

The Lonely Planet books are good and so are Rough Guides. Go to your library and check out some books. When you are ready to leave, purchase the ones you like. Make sure to get the most up to date edition.

Rick Steves has a good web site with info on Euro rail passes. It can get very complected. But once you choose, it is not hard to use them.

Lonely Planet is the best!
Lots of info on where to stay, including addresses, prices and recommendations.
I use them a lot and their recommendations are always spot on. (If they tell that the place is dodgy, avoid it.)
They also give info on eating, (from the cheapest markets to the best restaurants, with vegetarian and vegan options in almost every town,) going out for drinks, museums and sights with opening times, how to get to the place and how to get around there, all with prices which where correct when the guide went to print.

They come in different sizes, covering half the continent, or just a town.
Get the book that covers the area you want to travel.
If you travel most of the continent you might need the western and the southern Europe ones. (Or the Germany and France ones if that is what you think you travel.)

I have seen many people using Lets Go, but I do not think they are worth their money, nor the weight you would have to carry around.
An other thing to avoid is buying and carrying the photo guides.

But if you have a long time before traveling, do not buy the newest editions of the guides, get them second hand, from the library or from a remainders shop, and read before you travel.
In that case the photo guides are fun to use.
Also to use but not to take are the packet tour leaflets, see where they bring their people, and how much or little time they allow in each town.
Often they just skim the highlights, but sometimes you find a good one. (I found one for Australia that I used for small parts. I did most of the long distances by train or plane but joined the tours for the bits that are hard to do without a car, or sometimes even with a car.)

An other thing I would not do is 'Europe for so many dollars a day' or the books geared to midclass and expensive hotels.
The info on what to do in town is good, but you can get that info easily when you are there, but the info you need beforehand will be missing, the where to stay without paying a fortune.

And use Google, or one of the other search engines.
All you want to know is on the web by now.
If you enter the name of the country in the searchbar and train times, you get an English language train planner.
If you add tourist info, you get the English site of the national tourist office. (And a few commercial sites too.)

Enjoy your planning, take your time, first look at the countries you have always wanted to go, then see if you can combine them into a nice trip, remembering that the west of Europe is way more expensive than the east.