the difference between vista 32 and 64 bit

[timmythemoder]

i would like to know what the difference is between 32 and 64 bit and will all of my 32 bit apps work in 64 bit vista

[Gizmo]

32-bit Vista is subject to the same 2 GB memory limitation as all 32-bit versions of Windows (3 GB with some tweaking) unless you enable PAE, and even then, the application has to work with PAE.

64-bit Vista removes that limitation, enabling you to take advantage of more RAM (which Vista really needs; from what I've read, 2 GB of RAM should really be considered the minimum realistic configuration).

However, to run 64-bit Vista means that you have to have 64-bit versions of all your drivers. That can be somewhat problematic, ESPECIALLY for older hardware. TBH though, because of the changes in the driver model with Vista, that's not as much of an issue as it might otherwise be. Since a lot of vendors have had to release Vista specific drivers ANYWAY, most of them have released 64-bit versions also.

Yes, you can run your 32-bit applications on Vista. They run using WOW32. No, not World of Warcraft, rather 'Windows-On-Windows'. See, a WindowsNT-based OS (which Vista is) is built on a set of sub-systems. There's the NT Kernel and the native subsystem, which is where the lowest level hardware drivers live. Then there's the 16-bit OS/2 sub-system (which I think may no longer ship as part of Windows, but can still be installed from the Resource Kit). Then you've got the Posix sub-system (which has to also be installed from the Resource Kit, IIRC). On XP, 2K, and NT, you've then got the 16-bit and 32-bit Windows sub-systems. 16-bit applications are run using Windows-On-Windows, which essentially provides a 16-bit interface to 32-bit Windows. With 64-bit Vista, the 16-bit interface has gone away, and now you have 32-bit Windows-On-Windows, which interfaces to 64-bit Windows. (At least, that is what I read a while back: MS may have decided to keep the 16-bit sub-system on 64-bit Windows, since what I'm recalling was pre-release.) 32-bit applications will still be subject to the 2 GB memory limitation, but at least now they can each have their OWN 2 GB memory space, instead of being forced to share it with all the other 32-bit applications as well as the OS (assuming you have the physical memory to do so, that is).

[cloasters]

Thank you for that information Gizmo! Dell's higher end new PC's all come with 64-bit Vista, and many have 6 Gb of RAM. Seems that Vista is just a tad of a memory monster.