Update : I forgot to mention something , the Paris will be branded as an AMD Athlon XP and not as an Athlon 64.
The CPU codenamed Paris is expected to have 256KB of L2 cache, but it is currently unknown how much L2 cache the 90nm Victoria will have. The Paris CPU is expected to be avaible in the second or third quarter of 2004.
In order to replace the current Socket A platforms and force migration to the newer Socket 754 mainboards, AMD will make improved microprocessors that will be based on Athlon 64 architecture, but will be branded as “AMD Athlon XP” and will not be able to run advanced 64-bit applications for x86-64 architecture. Among advantages of the more powerful Athlon XP microprocessors, we should mention integrated single-channel PC3200 memory controller as well as SSE2 technology in addition to the improved architecture in general. Expect the Athlon XP microprocessors to perform better than current processors at the same speeds.
Provided that the rumoured information above is correct and AMD’s plans do not change, a year from now there will still be a bunch of 32-bit only CPUs from AMD. This means that software developers will not be very interested in optimizing their products for higher-end AMD 64-bit CPUs earlier than in 2005 or even later timeframe. This means that AMD may loose one of its very important advantages in case there are more 32-bit only processors than 32-/64-bit chips in the market.
Source : X-bit Labs