Thinking of Using an AMD Athlon Processor

I am thinking of assembling a desktop computer, because it much cheaper than laptop.  But I can be more mobile with a laptop, especially now that wifi internet connection is almost available in malls and restaurant.  I am planning to try out  an one of the AMD Athlon Processors available.  To see whether it is better than the other brand, based on what I heard.  The thing I like about assembling a desktop myself is that I can choose which brand to use, where to buy the parts and the most convenient time for me to purchase the parts.  I am planning to buy the parts one by one, when I only have extra money.  And match it with a 19" inch lcd monitor.  I’d like to have a computer that could run most of the best pc games available.