Simple one: How to set a static IP address?

I'm a bit new (or rather on/off) to Linux (but quite experienced with
Solaris). For fun I installed
Ubuntu on a spare PC and the it got an IP from my DHCP server. Now I
want to set a static
IP and edited /etc/network/interfaces to this:

# The loopback network interface
auto lo
iface lo inet loopback

# This is a list of hotpluggable network interfaces.
# They will be activated automatically by the hotplug subsystem.
mapping hotplug
script grep
map eth0

# The primary network interface
iface eth0 inet static
address 192.168.0.7
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255
gateway 192.168.0.2

Then I set IP on eth0 to 192.168.0.7 with ifconfig

However, from time to time, eth0 falls back to a DHCP address.
Do I really need to reboot, or have I set something wrong in the above?

.

Relevant Pages