Standard 63/37 solder has a melting point of 363 degrees Fahrenheit, why do people think it's going to melt under normal use? You've got to be kidding me. Most lead-free solder has a melting point of 5-20 degrees hotter than your standard 63/37, and anything with silver content is generally higher.
The reason you want to use a solder containing Silver is that regular solder dissolves silver (and gold). That being said, there is STILL lead/tin in solders containing silver. If there's no silver involved in your wiring, use a regular lead based solder as it's the easiest to work with and has eutectic properties (the different metals melt/harden at the same temperature, not separately).
My .02.
*edit* For those who want to read more:
http://en.wikipedia.org/wiki/Solder