Hi 657. Firstly can you please not use all capitals, it makes your posting difficult to read and is the online equivalent to shouting.
The AMD Duron is a cut down version of the Athlon. If on your computer you right click on "My Computer" and select "Properties", under the "General" tab you should see what processor (as well as what memory) you have. Generally there is an Athlon equivalent of any Duron, however depending on the age of your computer your choice may be limited. If you download and run Belarc Advisor click here, you should be able to find what motherboard you have. Post the results here and we'll see if we can tell you what processor choices you have.
Depending on what you use your computer for, you may not get a lot of benefit from changing to an Athlon. I'm using a Duron, and it does all that I require of it.