Can I unlock the prepaid Telstra HTC Wildfire and use a 3 SIM CARD?

yes indeed, i can recommend unlock codes from a href="http://www.wickedunlock.com/htc-wildfire/rs11wp9/" rel="nofollow"http://www.wickedunlock.com/htc-wildfire…/a to unlock your phone, since HTC is a 3G phone it works fine with all netwroks which Supports 3G.cost would be around 40$