Just a quick scenario for you.

You are using m$ on a network of 192.168.1.0 class C with a "residental gateway" in a workgroup called "workgroup".

PC1 net config

PC name "Computer1" (also the netbios name)
ip 192.168.1.25
netmask 255.255.255.0
gateway 192.168.1.1 (Only if you have broadband and are using a router, the "residental gateway")

PC2 net config

PC name "Computer2" (also the netbios name)
ip 192.168.1.26
netmask 255.255.255.0
gateway 192.168.1.1 (Only if you have broadband and are using a router, the "residental gateway")

If you are on broadband, don't forget to put in your ISPs DNS server addresses... or you get no naming resolution! Most of the time, your router will handle this for you, but some of the older "residential gateways" require you to actually enter the DNS into your network config.l

Check to see that in network neighborhood you have the same workgroup on both PCs.
If you are using XP or 2k, expect to have the same user ids and passwords on both PCs.

As long as you have the correct drivers loaded you should be able to ping back and forth or connect to shares, or use other resources.

You check your network settings by going to ms-dos prompt and typing

c:\ipconfig /all

that should list everything except for your workgroup.

Again, that is just a scenario...

Good luck!