Try this out, if you cannot get it working i can find out from my mate whom is an XP guru.
You need to enable the "File and Print Sharing" options in the network settings on the PC.
Then follow the below.
Now left click once on 'TCP/IP' in the list, and then on 'Properties'. A new window should open up. Now you need to choose a computer number, in the same way you chose one for your Amiga(s). It is essential that the number you choose (between 1 and 9) is different to any other computer number you chose for computers on your network.
This number will be for your IP address, in the form '192.168.0.X', and your hostname in the form 'computerX'. For instance, if I chose the number '3', my IP address would be 192.168.0.3, and my hostname would be 'computer3'.
You will need to cycle through each of the various tabs at the top of the TCP/IP window, to ensure the settings match the ones below.
o IP Address
o 'Specify an IP address' should be selected.
o 'IP Address' should be the IP address you worked out previously.
o 'Subnet Mask' should be '255.255.255.0'.
o WINS Configuration
o 'Disable WINS Resolution' should be selected.
o Gateway
o Fill in the IP addresses of each computer on your network, into the 'New gateway:' box.
o Remember to click 'Add' after each IP address.
o DNS Configuration
o 'Disable DNS' should be selected.
o Bindings
o The boxes 'Client for Microsoft Networks' and 'File and printer sharing for Microsoft Networks' should be ticked.
o Advanced
o 'Set this protocol to be the default protocol' should be unticked.
o NetBIOS
o 'I want to enable NetBIOS over TCP/IP' should be enabled (or it may be ghosted anyway).
7) You should now click 'OK' in the TCP/IP window.

You will now be at the main network configuration screen again. Click the drop-down text box labelled 'Primary Network Logon' and change it to 'Client for Microsoft Networks'.
9) Then click the tab at the top of the window labelled 'Access Control'. Ensure that 'Share-level access control' is enabled.
10) Now click the tab at the top of the window labelled 'Identification'. In the computer name box, delete any existing text, and type the 'hostname' you made up earlier.
11) Select the text labelled 'Workgroup' and delete anything that may be there. Type a workgroup name.
12) Finally, for the computer description, enter any text you like. Now click 'OK'. You will probably be asked to restart.
After you have restarted, you will be asked for a login username and password. Enter username and the password, and click 'OK'. After Windows has fully booted up, you should double-click on the 'Network Neighborhood' icon on the Windows desktop. You should see the drives of any other computers currently on the network.
If you wish to share a PC hard drive, you should double-click the 'My Computer' icon, and right-click on the hard drive you wish to share. A menu will pop-up. Select 'sharing'. A new window will appear.
If you wish to share a PC printer, you should go into the 'printers' folder, located in 'My Computer'. For each printer you wish to share, follow the same sharing procedures as described above for file-sharing, and choose any name you wish for the share name. You need to remember the share name you enter for your printer, because you will need it on the Amiga side.
Advanced users note: Should you wish to configure the Amiga Samba server(s), simply start an Amiga web-browser, and go to the website http://{ip-address}:901/ (where {ip-address} is the IP address of the Amiga you are configuring).