do have flashfxp? Set ip on xbox and pc like below PC ip 192.168.1.11 subnet 255.255.255.0 Xbox ip 192.168.1.111 subnet 255.255.255.0 gateway 192.168.1.11 Make sure you use "static" not DHCP
PC connect directly to xbox by using the crossover if you have. otherwise use 2 ethernet cable with hub or router.
FTP is a funny thing. everyone will tell you different settings as it really depends on your internet provider as much as your equipment. Like i have a cable modem going through a router and all of the information above is about the oposite of what my set up is. 1. my connection is set to DHCP on the Xbox and PC 2. i use a crossover cable, not eithernet 3. if PC is 192.168.1.100 then Xbox should at least be in the same range like 192.168.1.101 or 192.168.1.103 subnet mask and default gateway will be the same as what is on your PC. Your FTP program you will enter the IP address of the Xbox and the username and password are both xbox (lowercase) the default port is usually 21 and that can be left alone. you may need to try a few different set ups until you get it right.
