Since you have a quad, you have four cores. They are numbered 0, 1, 2, 3. CoreTemp reports the temperature of each.
The temperatures will vary based on how heavily any given core is used, and also because some cores might report themselves a couple degrees higher or lower than the others just to be different.
Bring up Task Manager and watch ythe utilization of each of your cores, and match that to the temperatures you see.
49 degrees for a core running hard in a quadcore is excellent. Don't change a thing.