Wbmw:
You make the argument that 32-bit processors won't be able to access the 64-bit features of Vista, but so far no one has listed which features these will be. There will be a 32-bit version of Vista, and what if it has 95% of the features in the 64-bit version? It would make the 32-bit argument silly.
Hmmm. You can run 64 bit and 32 bit applications simultaneously. You can't do that with a 32 bit only CPU. Programs won't be able to hijack system calls like they do in 32 bit XP in 64 bit mode. You can load larger images with 64 bit applications and separate multiple 32 bit applications into their own memory (no sharing needed). Video editting can deal with entire movies in RAM and have multiple copies, needed to be able to undo editting and video filtering.
Heck a standard ts video stream is 2.4MB/s. 2 hours of that is 17.28GB and that's for one copy. You would need at least twice that for before and after each change. There are just some applications that run far better with more than 4GB of total memory. Oracle is one off the top of my head. I'm sure that VLSI design and circuit simulation is far beyond being shoe horned into 4GB (actually 2-3GB in XP and Win2000). And it only takes one 64 bit application or a bunch of memory using 32 bit apps to push one into needing a 64 bit OS. Virtualization also begs for a 64 bit underlying OS.
Games now recommend 1GB (some talk of 2GB to work better) and GPUs are now up to 512MB (where you need 2-3 times that in memory space allocations to supply) and there can be 2 in SLI setups. Whoops, we are already over 4GB in allocations even with a single 32 bit game.
You say that 32 bit is good enough for laptop use. Thats the same tired old argument over the ages. Spoken every time the current limits were exceeded by something new. You could say the same thing about you really don't need 32 bits for laptop use. The 16 bit stuff was good enough. It was more efficient than today's bloatware and a 16 bit 286 or 68K are real sippers compared to Dothan or even Geode.
Sorry, but all it takes is the hint of something real soon now and the jump to the next level is on. Especially if the old stuff runs as fast or faster.
So Yonah can run the old ancient apps. It might be in some situations faster. But it will no be able to do anything with 64 bit. Turion can do everything Yonah can (sequential multitasking is typical and has a very long trouble free history) and so much more. So Yonah can run games and encode simultaneously at 170% as fast as Turion on a 32 bit OS. But Yonah runs XP, Solaris and Linux under VMWare at 1-5% as fast (if it doesn't crash) as Turion does. Swapping is such a morass for performance (like hitting a wall is one quote that comes to mind).
Where Turion could just demand page active memory areas because they are separate in memory space, Yonah has to swap entire program spaces to disk because they are in the same space. The latter works, but is ungodly slow compared to demand paging. That is why demand paging won out when the two were in competition (Intel and IBM took the program swap option and Motorola, Sun and DEC took the demand paging option).
Moreover, single core processors are never going to be able to get the benefit of dual core processing as more dual core applications become available,
This is total BS! All single core CPUs can run all threads of all applications using round robin (or some other type of) scheduling, swapping between active threads. So there won't be a single time where a SC can't run a dual (or more) threaded application. DC just allows for two threads being run at the same time. When, like most code, one thread is active at any given time, the SC runs at full speed, but the DC has one core that just idles doing nothing. And when the DC cores are slower than the SC core, the ratio is doesn't need to be too high for the SC to be overall faster than the DC.
In fact, IMHO, for laptops, the ratio won't get much above 110-115% of SC/DC clock ratio for same overall performance. For desktops it is more like 115-120%. Only in server work does the typical ratio get above 180%.
In fact, those very users that would pay the premium for DC on their laptops are the same ones who will want 64 bit. And AMD has the only options, A64 X2 and DC Opteron 1xx. Smithfield and Pressler are just too power hungry for that work.
Pete