Robert,
the TL072 you have is old technology and I don't think it can be used at all for your application.
The gain you would need for a span of 0 to 5000mV ( 5mV amplified to 5 Volt) is 1000! A gain of 1000 really needs to be done in two stages if you want any precision.
The gain needed also depends on the ADC you want to use. If you use a PIC with a 12bit ADC you could probably get away with less amplification then what you would need when using a 10bit ADC.
I hope I covered it all now.