All of the apologetics books suggested so far are good, and I can add a few more to the list:
Mere Christianity, C.S. Lewis
The Problem of Pain, C.S. Lewis
Miracles, C.S. Lewis
The Great Divorce, C.S. Lewis
The Everlasting Man, G.K. Chesterton
The Holman QuickSource Guide to Christian Apologetics, Doug Powell
Also, The Apologetics Study Bible (HCSB) is a good resource.
Now, how to get along with atheists...
I talk with atheists every day, both in real life and on message boards. We get along just fine. As with every conversation, the key is politeness and respect for the other person. But you don't necessarily have to go everywhere they want you to.
If you don't feel well prepared to debate a particular subject, or just aren't feeling like a debate that day, you can politely decline. Most of the time I am not interested in debate, though I do like interesting, thought-provoking conversation on most any topic. Don't allow yourself to be dragged or taunted into something you don't want to do.
Man's ego is inflated, his laws are outdated, they don't apply no more
You can't rely no more to be standing around waiting
In the home of the brave, Jefferson turning over in his grave
Fools glorifying themselves, trying to manipulate Satan
And there's a slow, slow train coming up around the bend.