You can do either or both of...
1) In VMWare set the client to have a bridge conenction to the host NIC, so it has it's own IP address (via DHCP or via fixed IP address) on any NIC that VMWare recognises... which will probably be all of the NICs that your host OS recognises. NIC = Network Interface = probably ethernet port, wifi card etc
2) Set VMWare to NAT to the host's IP... so transparently to you VMWare manages a tunnel from the guest OS to the host's network connection.
In effect (1) lets the guest run it's own connection and (2) sets up a natting router inside vmware... nothing much for you to set up beyond creating the NAT setup.
You use 'Edit this virtual machine's settings' button on the VMWare console to get to the dialo that lets you do both of the above.
Inside the guest OS, you 'just' configure the network interfaces as if they were running on a standalone machine *except* that they report themselves as an AMD NIC regardless of the type of hardware in your PC... that's how the VMWare emulated NICs look to the guest OS. So you may have to go find a suitable driver.
From experience I know that WinXP and Ubuntu both understand the network interfaces with no add-on driver stuff required.
Voice of experience - do not register your windows instance with Microsoft (if it's one that needs registration) until you've got all of the networking etc stable... or it spots that the 'hardware' has changed and required re-verification.
I've got Ubuntu7.10 and XP running as guests under Ubuntu6.06... it was nearly a doddle to do - the worst bit was finding the 'scsi' driver for the emulated disk to let XP install!