To share files across a network between computers there are several settings that have to be configured on both computers first. This is made a little more complicated in that you have computers with different OS versions.
Network: Your computers must all be residing on the same subnet. This means that if your if Computer A has an IP address of something similar to 192.168.10.10, your Computer B must also have an IP address of 192.168.10.11 where the final number is not used by any other device on the network and is between 1 and 254.
Workgroup: While not completely required, it is much more simplified to make sure that all computers in the network are in the same workgroup. When you open the control panel and go to System Properties, it will give you an area where the computer name and the workgroup name is listed. If the workgroup name is not identical on the computers, change it to something uniform on everything, such as OFFICENET, and then restart your computer.
Network Discovery and File/Print Sharing: You will need to enable on the computers the network file and print sharing options. This varies depending upon your OS, but the best thing to do is just google "Enable file sharing on Windows 7" and "Enable file sharing on Windows XP"
User Accounts: Sharing files between Windows XP computers without uniform user accounts or even having accounts with no passwords is alright, but Windows 7 really locks down on this as it's not near as secure to do. The way that they want you to do this is that every computer on the network should have a common user account with the same password on every computer. It uses this username and password to authenticate that you have access to shares and printers on other networked devices when automatically scanning the network for devices. This can be overcome, however, by allowing a folder to be shared to "everyone" which I'll explain below.
Folder Share Properties: These instructions are for setting up the share which is located on a Windows 7 computer, but the instructions will be similar on a Windows XP computer. Locate or create a folder you wish to share out on the network, and right click going to Properties. There will be a Sharing tab here that you can enable sharing of the folder (along with a label, I usually just use the default, but try not to use any spaces in the name of the folder, keep it simple!) You next want to go to Advanced Sharing and select Permissions. Here, the simplest and also least secure method is simply to select "Everyone" and check box Full Control to allow everyone on the network to have access to read and write data to the folder. However, the best practice here is to add individual user account names ONLY that will have access to the share. However, again this requires that you have user accounts set up across your computers with the same names and passwords so that the local computer can authenticate with other computers as the same user.
Mapped Network Drive: While this step isn't necessary to actually gain access to a shared data volume, it does make it much easier and quicker. Go to one of the computers that does NOT have the shared folder directly on it that you wish to connect to the share from. Open My Computer and click on Map Network Drive. Here you will select an unused drive letter and then enter the location of the shared folder. Sometimes you can Browse to it, but this often does not work properly. The best way to enter the location of the share is using the UNC path which goes like this:
\\"name of the computer with the shared folder without the quotations"\"name of the shared folder without quotations"
If everything has been set up right, it should create the connection and now show you a new drive listed in your objects in My Documents that points directly to that shared folder.
