I recently got an old Power Mac G4 from my school, since they were going to recycle it, and I am trying to get it to connect to the internet through my netbook, since it does not have a wireless adapter. Here are the specs:

Power Mac G4 Mirror Drive Door
1.25 Ghz PPC G4
1.5 Gb Ram
Geforce2 MX
80 Gb HDD
OS X Leopard Server Edition

Following some instructions online, I have converted an Ethernet cable to a crossover cable, but all the instructions I have seen have been for sharing the network to another PC, not a mac. Thanks for any help,

TC

If your netbook is running XP just set up ICS. Then you don't need to do anything on your mac (or even if it was a PC) because they just see the netbook as the real internet connection.

You will be happier with a router connection where the PC and the Mac attach to it.
Each system will then be independent of the other.

Use a regular cable (not cross-over) from the router to each system.

This will immediately give Internet access to all system.

Perform normal File/Sharing on the PC.

Accessing Mac => PC is via \\pcname\sharename

Accessing PC => Mac is via \\macname\macUserName

When I try to enable ICS, I get an IP conflict. ICS wants me to use the adress 192.168.0.1, which is the same as my router.

I can not hook the system directly to the router, because I would have to run a cable through a few walls to do so.

That's correct; ICS demands this address. Two choices; change the IP address of the router or cable directly ... but
can you use a wifi connection; the router and 2nd system needs to have WiFi.

The mac does not support wifi. I could buy an airport card for it, but I have not as of yet. Is is possible to change the IP of the ICS host so that it does not conflict with the router?

no. changing the router is trivial however; be sure to use a wired connection to the PC