It never hurts to have a bigger "thing".
Also known as heatsinks. They come in all shapes and sizes. The copper ones are very good, but are heavy and normally expensive.
Try to look for a heatsink with an 80mm fan. It will be able to blow more air over the heatsink without being too loud. Noise is a very big issue when it comes to heatsinks and fans
You could put a fan at the back of your case to expel the hot air coming off the processor. But you need to remember that air in = air out. The secret to cooling is good airflow. Even tidying all the cables inside so that air flows easily can make a few degrees of difference. Beware: you can spend a fortune keeping things cool.
If you have high temps, but don't have any stability issues, then there isn't a great deal to worry about. If you are getting lockups, or BSODs, then it could be a heat issue. It might just be that your heatsink isn't seated correctly, and needs to be refitted with some fresh thermal transfer paste.
As Choli said, sometime these temperatures are not always totally accurate. Even so, 61°C for an idle Athlon XP does seem a bit hot
