FC10 32-bit on an Asus Eee Box.

Start with a stock DHCP setup:

# cat /etc/sysconfig/network-scripts/ifcfg-eth0
# Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller
DEVICE=eth0
HWADDR=00:22:15:53:63:c8
ONBOOT=yes
BOOTPROTO=dhcp
USERCTL=no
PEERDNS=yes
IPV6INIT=no
NM_CONTROLLED=yes
TYPE=Ethernet

Then switch to a static IP via the GUI:

# usr/bin/system-config-network

click Statically set IP addresses:
Address: 192.168.0.162
Subnet mask: 255.255.255.0
Default gateway: 192.168.0.1
OK
File/Save

# cat /etc/sysconfig/network-scripts/ifcfg-eth0

# Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller
DEVICE=eth0
HWADDR=00:22:15:53:63:c8
ONBOOT=yes
BOOTPROTO=none
USERCTL=no
PEERDNS=yes
IPV6INIT=no
NM_CONTROLLED=yes
TYPE=Ethernet
NETMASK=192.168.0.1
IPADDR=192.168.0.162
GATEWAY=192.168.0.1

and you'll notice that the GATEWAY address has been
saved in the NETMASK address, rather than the requested 255.255.255.0

manual editing ifcfg-eth0 is necessary to recover from
the mistake made by the GUI.