You can use any solder. But i use Tin-Silver solder that you can find at radio shack.
Lead - High strength, low corrosive, high resistance [Melt temp: MEDIUM]
Silver -Highest strength, Low corrosive, low resistance [Melt temp: MEDIUM]
Tin - softens the metal alloy and decreases melt temperature. [Melt temp: LOW]
Gold - Low corrosive, lowest resistance [Melt temp: MEDIUM]
solder has more metals than just these listed*
eNeRGy: Keep that up, you will increase that motherboard's life.
sakobatoneko: don't get me wrong but 60/40 solder WILL work; i've done it when i have gotten short on time and $$