Here is a quick and easy way to share a Windows folder for OS/X to access:
On the Windows VM side (I am assuming you are using XP Pro):
1. Right click on the folder you want to share, select "Properties" from the drop down.
2. Click Sharing tag. Look at the "Network sharing and security" section in the middle. If this is the first time you do this, you might see some verbiage telling you to run a network wizard or just share without using wizard. Click sharing without wizard to reveal share folder options.
3. Check "Share this folder on the network", change the "Share name" if you want to, and check "Allow network users to change my files" if you want OS/X to write to that folder.
4. Click Ok.
5. Find the ip address of the XP VM. You can do that by running ipconfig in a Command Prompt window.
Now move over to the OS/X side.
1. In the Finder, Click "Go" menu, select "Connect to Server...".
2. Type smb://x.x.x.x/ in the Server Address: where x.x.x.x is the ip address of the XP VM. Click Connect.
3. If all goes well, you should see SMB/CIFS System Authentication dialog shows up. Enter your Windows user name and password. Click OK.
4. The next dialog allows you to choose which folder to connect. If you have shared more than one folders, pick the one you want from the drop down. Click OK.
5. Now the Windows folder should show up as a disk in OS/X.
Note: to maximize performance and to reduce network trafffic, create a Host-Only network for the Windows VM and use that ip address for connection.