Almost any formal emergency medical training is better than none, in my opinion. How much training, and which class to take depends on your situation, time, and budget.

Regarding EMT training, keep in mind that it is primarily oriented towards urban settings where the patient will be quickly transported to a hospital. In my opinion, a better option for survival situations is one of the "Wilderness" oriented classes. The reason being that these classes assume you might not be able to reach definitive care for many hours or days. They also stress improvisation, how to make do with what you have (not what might be found in a well equipped ambulance or clinic). Finally (and very important in my opinion) they usually give some guidelines about when to seek rapid evacuation, and when you might consider postponing a call for a helicopter (until the weather improves or until daylight, etc etc).

Within this context there are several options. There are various Wilderness First Aid classes that run about 16 hours, which are OK. A better choice if you can manage it would be a Wilderness First Responder (aka "WFR" or "woofer"). These run about 70-80 hours and cost $500-$600. Two good outfits offering excellent WFR classes that I can vouch for from personal experience are Wilderness Medical Associates ( http://www.wildmed.com/ )and WMI of NOLS ( http://www.nols.edu/wmi/ ). They offer classes in various regions of the country.