The Intel i865 is part of the Intel 865 chipset series. This chipset was released by Intel around 2004 and was primarily used in desktop motherboards for supporting Intel Pentium 4 processors. The chipset supports features like DDR memory, integrated graphics, and PCI Express.
The Intel i865 Windows driver refers to the software that allows the operating system (such as Windows XP, Windows 7, etc.) to communicate with and utilize the hardware capabilities provided by the Intel i865 chipset, including things like graphics, audio, LAN, or SATA support, depending on the motherboard's configuration.