The tank and heater sound good, you can also pick up a termometer at walmart for $2
I just bought, and am now cycling a walmart ten gallon.
In the 1/2 gallon you have now, due to the small size, you should do a 100percent water change every day. be sure to use waterconditioner and make sure the water temp is the same as the water he is currently in(here's where a thermometer comes in handy)
It will probably take a month for your tank to cycle so in the meantime you could buy a 2 gallon steralite container from walmart as temporary housing (2 gallons or larger) these are like $6 or something. That way you could put the heater in there and keep the fish warm while you cycle. But...you might need a heater in the tank you are cycling as well..
you can read about cycling here:http://www.bettafish.com/showthread.php?t=47838
you will also need to buy a freshwater test kit to cycle http://www.petguys.com/-317163010340...hannelid=FROOG
If you don't feel up to cycling just yet you could buy a 5 gallon critter keeper and do 100% waterchages in it once a week (with a partial during the week) They are about $15