Wireless networks are great for home networks, unless you need to copy large amounts of data around. OK, 802.11g is probably pretty fast, but I've got 802.11b here and when I tried to copy 4Gb of data around, things got a bit slow. I had no blank DVDs and my USB drive is only 1Gb so I had to figure out another way to get the data from one machine to the other. So I figured I'd network them the old way, with wires. And here, mostly so I remember how to do it next time, is what's required. This may not all be required but I'm a software man, not hardware, and you know how many software engineers it takes to change a light-bulb right? But given that most of the information I've found on t'internet seems to be "use a cross-over cable", it might be helpful to someone.
First, make sure the two computers are part of the same workgroup. Right click on 'My Computer' and view the computer's properties to see what workgroup the PCs are a member of. If they are on a domain, I guess they need to part of the same domain.
Next, the cable needs to be a cross-over cable. I think I, er, borrowed my cross-over cable from a former employer but they are available from all good computer equipment shops.
Next, make sure TCP/IP is configured to use fixed IP addresses. More often than not TCP/IP is set up to obtain an IP address automatically since they'll get assigned by your ISP or router or some little gremlin who sits in a box on the internet somewhere - look I dunnow how it works. Here your TCP/IP connection is just between two computers, so there is no little gremlin to assign IP addresses. So look at the properties of your network connection and from there look at the properties of the TCP/IP stack. I think you can pretty much choose whatever IP address you like, so long as the two PCs have different IP addresses. I chose 100.100.100.101 and 100.100.100.102 and that worked fine.
Finally, disable your wireless connection on one PC at least. This may well make no difference at all, but it seemed like a good thing to do. If your PC can see another computer via two network connections, how does it choose which connection to use when copying files? Again I don't know, so figured disabling the slow wireless connection would be a good idea.