How often you strength train depends on your goals. To increase strength I'd go towards the high end - like the other posts mentioned about 3 times a week. Once you've reached your strength goals, to maintain you only need to go 1-2 times a week. Allow 48 hours of rest as they mentioned.
I've also noticed I'm the most sore the day after I lift, so this is where it's good to allow the 48 hours rest. I.E. I can't do squats on Monday and expect to run on Tuesday! : /
"I have a personal relationship with food. I love it, but it's on the fence about me." ~Kathy Griffin
"If there was a famine, we'd be the last to survive." ~My mother
| current weight: 137.8