Actually, the P4 is not really an 'embrace and extend' strategy, as you suggest. They're really just trying to get rid of the really crappy x87 FPU (which is horrid). SSE2 is an ISA - the P4 is just an implementation of it. Future AMD processors will also feature SSE2. (SSE2 will be like MMX in this regard). Hurray for this! Down with x87! Nick Reinking