Thinking about buying a programmable thermostat - doing homework first

I currently live in an apartment, and I currently have a trane thermostat ; I want to replace it with a programmable honeywell thermostat located here: Honeywell | Wi-Fi Smart Thermostat (http://yourhome.honeywell.com/home/Products/Thermostats/7-Day-Programmable/Wi-Fi+Smart+Thermostat.htm) I have read the manual for the thermostat I want to buy - before buying it (I don't want to buy it then try to "wing it" and find out I can't use it) - but I guess my trane is old I am missing 3 wires to match Here is what my Trane looks like: Attachment 38804 (http://www.doityourself.com/forum/attachments/thermostatic-controls/38804-thinking-about-buying-programmable-thermostat-doing-homework-first-imgp0791.jpg)