[CentOS] Network configuration question

Hi,

My wife and I live in a two-storey flat, and we have a small home LAN 
(100% CentOS 5) with a "classical" configuration:

On the ground floor, there is the telephone jack with the DSL modem 
router (192.168.1.254). This modem has a mini-switch with two Ethernet 
jacks to it, and the two are used by:

- the server (192.168.1.1), a "black box" running in a cupboard 24/7
- the wireless AP (192.168.1.253)

Then, on the first floor, everything is connected by wireless, and for 
the moment, configured statically:

- my desktop PC (192.168.1.2)
- my laptop (192.168.1.3)
- my wife's laptop (192.168.1.4)

I have an older laptop here, a Fujitsu Siemens Amilo D, that I'd like to 
use as a simple build box. It's physically installed next to my desktop 
PC. It doesn't have a wireless card, so I vaguely thought: is it somehow 
possible to connect this laptop with an Ethernet cable to my desktop 
PC's unused Ethernet card, and then connect it to the internet? In that 
case, I wonder if I have to bridge the desktop PC's network interfaces 
(wlan0 and eth0). That said, I don't even know if the driver for wlan0 
(rt61) allows any bridging. Or maybe simply configure a different 
subnet, but then, what would the network configuration look like on the 
laptop and on the desktop PC?

Any suggestions for that?

Cheers,

Niki