I think that it depends on the processor itself and the type of cooling you have. I have an Athlon XP 2500 (barton) oc'd to the XP 3200. I upgraded from the stock heatsink/fan, and I also have 2 more fans for cooling. My cpu is usually between 38 - 44 degrees celcius.
Now, my sister has an older Athlon. I think it's the 1800. My brother and I have thrown everything we can at it as far as cooling(exception being water cooling!!). Her cpu runs between 70 - 74 degrees celcius!!
Anyone correct me if I'm wrong, but I would say cooling and the type processor you have is the cause. While your temps are pretty warm, they're not fatal to your cpu. Although, if you're still running stock heatsink/fan, look for an upgrade....it should definitely help bring your temps down.