The only good way to start a road trip is with Willie Nelson "On the Road Again"
You're driving a truck from Texas to Atlanta...gotta be Jerry Reed
Both good suggestions... I also used to like listening to Ghost Riders In The Sky when I was out on a western trip. And Nick nailed it...
As for music? Check out Pandora if you have a mobile device, and if you can connect it to the truck's stereo, you'll have anything you want at your fingertips (and free). I love Pandora, and rely on it heavily for these types of drives.
As long as you won't run into a data plan cap, using one of the suggestions above to start with on Pandora would work great, and you're likely to discover some new music that you like, too!
I've never listened to those before. Where would be a good place to find them?
Diana!
You've never listened to The Pilotcast?!?
Probably the easiest way is to go into the iTunes store, click on Podcasts, and just do a search for "Aviation."
My favorite show that isn't The Pilotcast is
Airspeed, and I think you'd really like it. Some particularly good episodes: First Solo, The Guy In The Red Airplane, The Ballad of Jimmy Short, Fingers In The Airport Fence Entwined, The Magi Of Harper's Field, the Airspeed Safety Stand-down, and there's several interviews with aerobatic pilots as well as Steve's own thoughts about his start in aerobatics. There's also a couple of good songs - I particularly like "Eleanor Flies" but "Hey Don" is another good one.
Load up your Ipod with a couple good books-on-tape. Your public library probably has several hundred to choose from; worse case you can rent them from Cracker Barrel.
That's a good one too. You can get them on iTunes as well and not have physical media lying around - My favorite audiobook is Rinker Buck reading his "Flight of Passage."
I just found out what size truck I'm driving. It's a 26' truck. Haven't ever driven a truck that long. Helpful hints? Suggestions?
You've gotten quite a few on how to drive the truck, and they seem generally good. The first one I thought of is that you'll need to watch the swing of the tail like Stacey said.
What you haven't gotten is much about what everyone else will do. You'll be appalled at how people drive around larger vehicles. You'll find that people get way too close in front of you. You'll also find that when you flip your turn signal on to pass someone, that often a car that's behind you or a ways back in the left lane will suddenly accelerate and try to "block" you.
Basically, expect people to do the stupidest possible things, and be pleasantly surprised if they don't.
Also, while you're not going to be accelerating or stopping nearly as fast as you're used to, try to keep it even less. Especially with braking, if you push 'em too much you're going to be breaking stuff in the back. Use 'em if you need 'em, but the less you push down on the pedal, the better.
Finally, if an animal runs out in front of you - Kill it. Sounds terrible, but you cannot swerve these things like a car - You'll roll over. Hit the brakes, sure, but do NOT move the steering wheel more than a bit. The only time I broke this rule was when a PERSON suddenly appeared in front of me in the middle of the night on a state highway in Kansas.
Countersteer and full-width shoulders allowed me to save it without hitting her but it was CLOSE. I say again,
Enjoy the trip and drive safe!
That's funny. 
