Please Help Me Figure This Out!

OK - as some of you know - I am only working PT right now - still interviewing and hoping for a guidance counselor job. In any case, my friend just called me up to see if I was interested in some temporary work - her friend's nanny quit and she is in a bind and they need to interview for a new nanny but need someone to be with the kids until they hire a new nanny. I don't know anything about hours or salary until I speak to this woman - but can anyone who has experience with this give me an idea of what is a fair salary to get? I haven't babysat since I was a teenager - so I don't know what is appropriate for an adult to get to be a temp nanny - they also live about half and hour from me and there are two boys - 5 and almost 2. I think she is calling me tomorrow so any hints would be appreciated!
Thanks!