CHalsey
To go online, you need to install the following:
1st) DSS (Desktop System Software)
2nd) Chipset
3rd) Network Driver.
Yes, the drivers with the check mark should be compatible.
For the video driver, you need to find which Video card was installed, are you still using the default video card, the system was shipped with?
http://www.dell.com/support/drivers/us/en/19/Product/dimension-8400?s=dhs
The Dimension 8400 was shipped by Dell with one of four different PCI Express x16 video cards.
Bev.
