I've created in NI Multisim 11 project PT1000 and OP Amp TLC271CP for measuring temperature from-20C to +200 C. It should formula for calculation Vout and to check whether this model can work in reality. I am not electrician but my Hobby's electronics. Intervals Vout (ADC) is 0-5 V. Microcontroller was ATMega 16, but that does not meet, if resolution ADC ATMega 16 is not good I think to use SPI MCP3201 12-bit ADC. Further should formula for calculation RT (R7) on bases Vout.
921.6Ω -> 0V and 1758.6Ω -> 5V Formulas for this circuit see: http://www.maxim-ic.com/app-notes/index.mvp/id/3450 http://www.umnicom.de/Elektronik/Schaltungssammlung/Temperatur/Pt1000/Pt1000.html The TLC271 ist not a precision OpAmp, even with 0.0001% resistors the deviation may be up to -5C to +5C of real temperature. Better use an OpAmp with Vos below 1mV.