Directly download links for most of the famous NIC drivers are listed here.
Including Intel, Broadcom, Marvell & Realtek.

Intel PRO/1000 & PRO/100 Network Adapter Drivers for:
Windows 2000, Windows XP & Windows Server 2003 Version: 13.0 (Detail)
Windows XP x64 & Windows Server 2003 x64 Version: 13.0 (Detail)

Marvell Yukon Family for:
Windows 2000, WIndows XP & Windows Server 2003 (32-bit and 64-bit) Version: 10.55.3.3

Realtek RTL8111B/RTL8168B/RTL8111/RTL8168/RTL8111C PCI-E Gigabit Network for:
WinXP 64/Win98SE/WinME/Win2K/WinXP (Version: 686, Date: 2008/03/26)
Vista 64 and Vista (Version: 6.203, Date: 2008/03/26)

Realtek RTL8110SC(L)/RTL8110S-32/RTL8110SB(L)/RTL8169SB(L)/RTL8169SC(L)
RTL8169 PCI Gigabit Network for:
WinXP 64/Win98SE/WinME/Win2K/WinXP (Version: 687, Date: 2008/03/26)
Vista 64 and Vista (Version: 6.203, Date: 2008/03/26)

Broadcom NetXtreme 57xx Network Adapter for:
Windows XP & Windows Server 2003
Windows XP x64 & Windows Server 2003 x64