Can't think of any reason changing the ink cartridges should effect the internet connection.
If I understand the problem:
Cable Modem --------> Belkin Router ---------> Desktop
No internet connection for the desktop.
Are you sure the Desktop is connecting to the Belkin? Can he access the Belkin's user interface from the desktop? If he can acccess the Belkin, then the card and cable is probably OK.
Did he try connecting directly to the cable modem to see if that works?
If you connected wireless, try connecting your laptop by the same ethernet cable to see if that works?
Could you supply the followong information for the desktop?
Taken from a JohnWill post.
Hold the Windows key and press R, then type CMD to open a command prompt:
In the command prompt window that opens, type type the following commands, one at a time, followed by the Enter key:
Note that there is a space before the -n or the /ALL, but there is NOT a space after the - or / in the following commands.
NBTSTAT -n
IPCONFIG /ALL
Right click in the command window and choose Select All, then hit Enter to copy the contents to the clipboard.
Paste the results in a message here.
If you are on a machine with no network connection, use a floppy, USB disk, or a CD-RW disk to transfer a text file with the information to allow pasting it here.