Internet Sharing via Ethernet with PC

[twister]

I'm posting this hear because you are all smart. Hopefully someone can help.

Short: How can I setup a Windows XP machine to share it's wireless internet via the ethernet port with another Windows XP machine?

Long: We have wireless internet at work and no wired ports in the offices. One machine in the office must be connected to the network via an ethernet cable due to circumstances outside our control.

Now, when I have my MacBook Pro, it's dead simple to share my wireless internet with the XP machine via the ethernet port. But I'm getting tired of always having to work around others schedules as they need to piggyback off my Mac.

So my question is, how do you setup the same functionally from one XP laptop to another?

We've tried and followed tutorials and none have proven us successful? If anyone has any good tips, or reliable sources, please do share.