Intel - http://downloadfinder.intel.com/scripts-df/support_intel.asp
ATI - http://www.ati.com/support/driver.html
Matrox - http://www.matrox.com/mga/support/drivers/home.cfm
Nvidia - http://www.nvidia.com/content/drivers/drivers.asp
3Com - http://support.3com.com/infodeli/tools/nic/
US Robotics - http://www.usr.com/support/
SIS- http://download.sis.com/
Via - http://www.viaarena.com/?PageID=2
MSi - http://www.msi.com.tw/program/support/spt_index.php
Acer - http://support.acer-euro.com/drivers/
Creative - http://www.europe.creative.com/support/drivers/
Lexmark - http://downloads.lexmark.com/en/us/index.html
Epson - http://emeasupport.epson-europe.com/downloads.aspx?LNG=en-EU
Brother - http://www.brother.com/E-ftp/softwin.html

links to certain PC manufacturers:

HP/Compaq - http://welcome.hp.com/country/us/en/support.html
HP/Compaq - http://h18007.www1.hp.com/support/files/
Dell - http://support.euro.dell.com/uk/en/home.asp
IBM - http://www.ibm.com/support/us/
RM - http://www.rm.com/support/knowledgelibrary.asp?mode=SerialNoSearch
Gateway -  http://support.gateway.com/support/drivers/dlcenter.asp