Can you a network have both wireless and wired?

I currently have internet service and a D-Link switch hooked up to Computer
A (running XP home). Computers B and C both use ICS and the network works
flawlessly. My question is, I want to add a wireless connection for my
laptop (computer D). Is it possible to run a wired and wireless network from
the same computer (computer A)?? I have one open spot on my D-Link switch,
would the wireless base just connect to that port rather than the computer
NIC card?

Before I put out the money on this, (really don't have the $$ to make the
whole thing wireless just yet), I want to make sure it's possible, and how
complicated it will be.

Thanks
David Nelms