AMD recently adjusted prices for its current desktop processor line, the biggest change is seen on Athlon 64 models that have seen cuts of up to 30% making them much more attractive to buy while the enthusiast/gamer oriented FX CPUs have seen an actual increase on its price.
The Register has a complete table with old and new processor pricing as well as details on older Athlon XPs that are being discontinued.
Update: On a related note, Microsoft won't be releasing 64-bit versions of Windows XP or Server 2003 until the first half of 2005 (thanks Mike Larson).