Here it is, plain and simple:
Buy this for cheap:
http://www.amazon.com/Garmin-Forerunner-Receiver-Heart-Monitor/dp/B000CSWCQA/ref=sr_1_1?s=electronics&ie=UTF8&qid=1307032419&sr=1-1
don't buy this:
http://www.amazon.com/gp/product/B004XC3MXI/ref=cm_cr_mts_prod_img
Save yourself $270+ dollars...