Change to 2 interfaces on 1 NIC?

[Mark Neidorff <mark@neidorff.com>]

Hi all,

I currently have my 6+ year old server (web, e-mail, firewall, local lan) 
running with 2 NICs, one coming from the DSL router (on the 192.168.2.x lan) 
and the other connected to the local lan (192.168.1.x). (all local users get 
their mail, web surfing and firewall services from my box) I only use static 
IP addresses. This server is a big, old and noisy box and I want to use a 
small, quiet mini-itx box in its place.  The new mini-itx box that I just 
bought has only 1 NIC port.  The example for setting up multiple IP addresses 
from the network configuration page looks like this:

auto eth0
iface eth0 inet static
    address 192.168.1.42
    netmask 255.255.255.0
    broadcast 192.168.1.255
    gateway 192.168.1.1

auto eth0:0
iface eth0:0 inet static
    address 192.168.1.41
    netmask 255.255.255.0
    broadcast 192.168.1.255

auto eth0:1
iface eth0:1 inet static
    address 192.168.1.44
    netmask 255.255.255.0
    broadcast 192.168.1.255

This is the way my current 2 NICs are configured (yes, the config is from RH, 
but the concepts are the same):
#eth0 connects to the router
DEVICE=eth0
BOOTPROTO=static
IPADDR=192.168.2.2
NETMASK=255.255.255.0
GATEWAY=192.168.2.1
ONBOOT=yes

#eth1 connects to the local lan
DEVICE=eth1
BOOTPROTO=static
BROADCAST=192.168.1.255
IPADDR=192.168.1.1
NETMASK=255.255.255.0
NETWORK=192.168.1.0
ONBOOT=yes

My questions:
1.  Are all 3 of the interfaces shown usable, or does the first "auto eth0" 
define the NIC for the others?
2. Can I put an address like 192.168.2.2 for one "iface" (like eth:0) and 
192.168.1.1 for another (eth0:1) or will this not work, and I will need a 
mini-itx with 2 NICs?

thanks,

Mark