For the desktop, 64 bits will become significant in about 3 years I reckon, when we start seeing desktops with more than 3GB of RAM. Think video editing.
For servers, 64 bits is needed now. RAM is getting very cheap, it's great to be able to in-memory 30GB databases.
One thing that journos often miss about the AMD64 is that it actually has a lot more registers than the 32 bit i386 line, so when we start seeing specially compiled apps there should be a significant performance boost from that alone. Also the AMD64 can switch between 32bit and 64bit under program control, so you can have the best of both worlds.
Lurking ... as I sit at my desk at ... Intel
You don't load an entire video into memory at one time because that isn't needed for non-realtime editing.
For servers, 64 bits is needed now. RAM is getting very cheap, it's great to be able to in-memory 30GB databases.
I'm more interested in CPUs for Joe-Six Pack.
One thing that journos often miss about the AMD64 is that it actually has a lot more registers than the 32 bit i386 line, so when we start seeing specially compiled apps there should be a significant performance boost from that alone. Also the AMD64 can switch between 32bit and 64bit under program control, so you can have the best of both worlds.
AMD was nice enough to send me all five volumes of the AMD64 Programmers Manual. The extra registers are about the only interesting thing to me (the floating point mods are good). Of course, there's always a trade off when it comes to a big register set.