Changes

* Although some code may slow down ~10% with longer addresses, use of the XMM registers greatly speeds up some code as well. Overall, I would expect performance to be about the same based on other benchmarks. Not everyone will be able to run these binaries, but, IE8 on Vista 64 already has these enhancements, and I would hate to see Firefox not have them available.

* I've heard a lot of good feedback on the chrome download manager - can we spend some time during the prototyping period to look and see if we can make some improvements?