1----> there are many software tht convert png to icon with alpha, 32 bit, transparency, support
They r Articons, IconXP, Any to Icon
u can get them on
www.download.com.
As these r shareware u can use them tll 30 days.
So thing is download all the three install one every mont thus making the conversion period till 90 days
or better get a crack of any of them
2-----> Chanking icons like Reclycle . my competc
Assuming u r using XP then
a) right click --> properties --> Desktop
b) customize desktop.Then select any thing tht u want to change then change icon
OK