I would like to built a Weather Station to monitor only the temperature and transfer the data to my PC. I was wondering if you have any advice? any links or books.
(I DON'T WANT TO BUY A WEATHER STATION!; I would like to built it)

I have a PC, a digital thermometer. I guess that I will need some kind of acquisition card
best regard
kh

I would like to put a temperature sensor in every room
and monitor the different temperature. It will help me to balance my Heating/AC system?

If you'd want to regulate the temperture on your house on a per room or per zone basis you would need a more complicated thermostat as well as additions to your current ductwork to support only blowing the hot or cold air to the zones that need them. Unless you have a 10,000 sq ft house I don't recommend investing in this. It's just not worth it.

You will need to build a device that converts the information from the weather station into a digital format and connect it to the serial port o your PC.

....and then some software to interpret the digtital information from the serial port and present it to you in a useful format.

White-Rogers makes an averaging thermostat that can interconnect with up to 3 room sensors. The thermostat takes these inputs and averages them out and then decides how to cycle the heating/cooling to achieve the best "curve" in comfort and effiency. If your interested I can obtain which model thermostat offers this.