The WoW64 subsystem is limited to the so-called user mode, i.e., applications launched by the user. When operating in kernel mode, all files have to be available in 64 bit format.
Since all device drivers require kernel-mode access, it is no longer possible to use 32 bit drivers, even if they were written specifically for Windows Vista. Also, not all device drivers that Microsoft offers through Windows Update are available as 64 bit drivers. This also includes devices that you may be used to attaching quickly and simply via USB.
Especially problematic are more exotic devices, such as older scanners or COM-port adapters; these may encounter driver problems and may thus not be usable under 64 bit Windows.
CoreTemp won't run in the standard Windows configuration
Without a proper driver, the application is unable to display any readings.
In some cases, you may need device drivers even without using hardware. One such example would be applications that read data from the CPU or memory using the SM-Bus. While CPU-Z and Speedfan ran flawlessly, we had to disable driver signatures for CoreTemp, even though it possesses a 64 bit driver component. Copy protection drivers used by older games may also cause problems. Games that carry the "Games for Windows" logo, on the other hand, are safe and will run smoothly.
I have 1 GB of RAM and am using 80% after a normal boot (plus a few non-essential apps... but they make doing things easier
Did I miss something?
Nevertheless I've already built a system with Vista 64 & 8GB ram few weeks ago and wanted the test to comfort decisions I made.
Also, is the reason that only 3.5GB is available in the 32-bit environment due to the 512mb video card and MMIO? If so, what will happen in a 32 or 64 bit system if you have a video setup with 2gb of video ram? Will you only have 2GB of main memory available?
Significant chunks of address space below 4GB (the highest address accessible via 32-bit) get reserved for use by system hardware:
• BIOS – including ACPI and legacy video support
• PCI bus including bridges etc.
• PCI Express support will reserve at least 256MB, up to 768MB depending on graphics card installed memory