WARNING---------R/C cars and planes are addicting.
I have 6 cars/trucks, 3 planes and a half finished boat. I really love the products from Team Associated. They are really durable and easy to work on. The Losi vehicles are durable too, and handle great but I have always found them a pain in the a$$ to work on. Traxxas also makes some awesome backyard bashing vehicles but I've never been a fan of the Maxx series, Too heavy, under powered and bulky.
Nitro cars are a blast, If you're mechanically inclined you'll have a blast. If not the learning curve can kill ya. Once you get the hang of them there's nothing better.
It all depends on where you plan on running your car as to what kind you should get. Monster trucks are all the rage these days for terrorizing playgrounds and BMX tracks. I'm a fan of the stadium trucks. They're high enough to bash around with, yet still have the low center of gravity, suspension setup, and light weight to give them tremendous speed and agility. There are some wickedly fast on-road cars out there these days too. Just match the style of vehicle to what you want to do with it and you'll be happy.
As tjthorson said, some radios have a built in failsafe. If not they can be bought seperately added in-line with the throttle servo for around $20. It's a good idea. I have an 1/8" aluminium chasies hanging on my shop wall that looks like a potato chip. (it used to be flat) I had a radio failure and my RC10GT went wide open for about 400 Ft before squareing up with a curb.
The curb won. Even so, I believe it cost less than $50 to get me up and running again.