CAT5 and Firewire LAN Connections

Is it possible to created a Firewire LAN connection between two PC's and
also continue to use the existing LAN connection?

Senario:

4 PC's all conencted to a 10/100 Switch via CAT5

2 PC's have FireWire, I have attached a FireWire cable connecting these two
PC's, I want to be able to access PC1 from PC2 via the firewire card to take
advantage of the extra speed. But still connect to the LAN to access
internet (router), and other pc's.

I can't see why not, I am just unsure of the IP address and Gateways to use,
my existing network is using

IP/Range: 192.168.1.x
NetMask: 255.255.255.0
Gateway: 192.168.1.1

Thanks

diagram:


-------
| PC1 | ----------
------- |
| (firewire) |
------- |
| PC2 | ----------
------- |
| Switch
------- |
| PC3 | ----------
------- |
|
------- |
| PC4 | --------
-------