If you're going to set up a permanent network, I suggest a Linksys wireless router. I have a WRT54G V4 (one of the best, even better than some newer models) and a wired BEFSR41 I found at a garage sale for $5.
The problem with routers is that you have to be somewhat network savvy to set them up quickly. Your other option is to acquire a network hub or switch. They're essentially dumb, meaning you don't get anything in the way of efficiency or security, but they're fine for offline networks, or behind a router.
With a hub, you can just set both comps to be in the same workgroup (MSHOME, WORKGROUP, whatever), enable file sharing (I just share entire drives, it's faster and less confusing to new users), and go.
I'm making it sound more complicated than it is...
http://www.wown.com/