Instead of explaining it myself, I'll let someone who has to maintain a kernel with PAE support speak in his charming ways, Linus Torvalds

• PAE sucks (Why didn't MS take advantage of PAE?)

Also keep in mind that the PAE support in Windows 32bit versions comes for a lot of cash. XP won't even be able to make use of full 4 GiB of RAM normally, because MS chose to not enable PAE features on it. A kernel that is closely related, Windows 2003 Server, does support PAE. However, even there your "Standard edition" will only support up to 4 GiB (but working around the BIOS memory hole), whereas the more expensive editions will then allow up to 64 GiB of RAM. The same holds for 32-bit Vista.

However, not in all cases is this limitation imposed by Windows. If it were, booting a PAE-enabled Linux kernel would still enable you to use the full 4 GiB (or more). Not so, some hardware manufacturers chose to impose this limitation at the BIOS level, although the CPU and chipset would be capable of handling PAE.

Just a side-note: none of the current x86-based 64bit processors can even address the full range of the 64bit address space physically (for reference see this question and answers).

Instead of explaining it myself, I'll let someone who has to maintain a kernel with PAE support speak in his charming ways, Linus Torvalds

• PAE sucks (Why didn't MS take advantage of PAE?)

Also keep in mind that the PAE support in Windows 32bit versions comes for a lot of cash. XP won't even be able to make use of full 4 GiB of RAM normally, because MS chose to not enable PAE features on it. A kernel that is closely related, Windows 2003 Server, does support PAE. However, even there your "Standard edition" will only support up to 4 GiB (but working around the BIOS memory hole), whereas the more expensive editions will then allow up to 64 GiB of RAM. The same holds for 32-bit Vista.

However, not in all cases is this limitation imposed by Windows. If it were, booting a PAE-enabled Linux kernel would still enable you to use the full 4 GiB (or more). Not so, some hardware manufacturers chose to impose this limitation at the BIOS level, although the CPU and chipset would be capable of handling PAE.

Just a side-note: none of the current x86-based 64bit processors can even address the full range of the 64bit address space physically (for reference see this question and answers).

Instead of explaining it myself, I'll let someone who has to maintain a kernel with PAE support speak in his charming ways, Linus Torvalds

• PAE sucks (Why didn't MS take advantage of PAE?)

Also keep in mind that the PAE support in Windows 32bit versions comes for a lot of cash. XP won't even be able to make use of full 4 GiB of RAM normally, because MS chose to not enable PAE features on it. A kernel that is closely related, Windows 2003 Server, does support PAE. However, even there your "Standard edition" will only support up to 4 GiB (but working around the BIOS memory hole), whereas the more expensive editions will then allow up to 64 GiB of RAM.

However, not in all cases is this limitation imposed by Windows. If it were, booting a PAE-enabled Linux kernel would still enable you to use the full 4 GiB (or more). Not so, some hardware manufacturers chose to impose this limitation at the BIOS level, although the CPU and chipset would be capable of handling PAE.

Just a side-note: none of the current x86-based 64bit processors can even address the full range of the 64bit address space physically (for reference see this question and answers).

Instead of explaining it myself, I'll let someone who has to maintain a kernel with PAE support speak in his charming ways, Linus Torvalds

• PAE sucks (Why didn't MS take advantage of PAE?)

Also keep in mind that the PAE support in Windows 32bit versions comes for a lot of cash. XP won't even be able to make use of full 4 GiB of RAM normally, because MS chose to not enable PAE features on it. A kernel that is closely related, Windows 2003 Server, does support PAE. However, even there your "Standard edition" will only support up to 4 GiB (but working around the BIOS memory hole), whereas the more expensive editions will then allow up to 64 GiB of RAM. The same holds for 32-bit Vista.

However, not in all cases is this limitation imposed by Windows. If it were, booting a PAE-enabled Linux kernel would still enable you to use the full 4 GiB (or more). Not so, some hardware manufacturers chose to impose this limitation at the BIOS level, although the CPU and chipset would be capable of handling PAE.

Just a side-note: none of the current x86-based 64bit processors can even address the full range of the 64bit address space physically (for reference see this question and answers).