I upgraded my machine from a Sempron 3000 to an X2 5400 and it's running
too hot, about 55c average, jumps to 62-65 under load. I'm using the stock
heat sink/fan but I still don't think it should get that hot. I have no
case fans.

According to Speedfan my temps under load a
temp1: 64
temp2: 46
temp3: 25
hd0: 47
hd1: 48
temp1: 30
co 66

Rosewill case
ECS 6100 MB

What is my best bet? A fan for the side of the case?