Are you sure you need a PT100? it is fairly difficult to get that connected to a computer, and the sensors themselves are expensive.
You will need a precision current source, some way of adjusting for lead resistance, and a precision A-D converter. That needs a skilled electronics design guru.*
Then you will need to write the drivers to receive the digital value and convert it into a temperature using a calibration curve that you have produced.
It's certainly all possible. I was considering doing it myself until I found how cheap and easy to use DS18B20
s are. In view of those, the only reason for using PT100s would be if the sensors already existed or were specified, or if you needed better than 0.5C repeatability.
* Or buy something that does the same job