5 or 5e is likely what you'd use with your cable modem. 5 is spec'd for 10 baseT while 5e is for 100.
To reconfig your desktop IP, go into Start>Settings>Network and Dial-up Connections.
Right click your connection and view properties.
Highlight "Internet Protocol (TCP/IP)" in the list (you may have to scroll to see it) and click the properties button.
Click the radio button for "use the following IP address" and type in 192.168 ... that I posted above. Make sure you do NOT give your two machines the same address.
Connect cable, FTP away.
To set back, repeat the above but click the radio button for "obtain an IP address automatically."
*NOTE: if you have some custom IP configuration already set up - i.e. the "use the following IP address" button is checked, do not mess with this unless you know what you're doing.
-Matt