Hi there.
You don't need a "Real" Network card in a VM running under vmware or vbox. The "Virtual Network adapter" installed when you create the machine will handle all the network stuff. This is all done at Creation time of the Virtual Machine automatically provided you enabled Networking in the setup / configuration file.
You can add it in afterwards if you forgot it.
(Some commercial servers can connect physical NIC's to VM's via a "Vswitch" or PCI pass through but for home applications this is usually overkill - VBOX / VMWARE desktop products don't need this capability so you can ignore it).
so :
Ensure that
1) you have at least "Host Only" networking enabled ( in the configuration file for the VM)
2) Folders / directories / drives are marked as SHARED on the relevant machines (including the VM's) and you have access (read / write or whatever)
3) Ensure Firewall access doesn't prevent you from connecting to the relevant machine
4) You need to have an account AND password (usually) on the machines you want to access the devices from.
Then it all works fine
Here's an example of a W7 Host accessing a W2K3 server Virtual Machine
I've also shown an image of the configuration file -- I'm using vmware's ESXi so the configuratiuon is slightly different to what you will see but you should definitly see a Virtual Network adapter
Cheers
jimbo