generally no. It's not a feature most motherboards supply. A good quality wireless card will only cost you ~$30 though. Consider the placement of the desktop though if you are going wireless.
I have wireless myself, and sitting under my desk it receives a rather poor signal. So I also have an external antenna (just one that screws into my wireless card but has a long cord and sits up on my desk) to improve that... which was another ~$10.
Even the smallest donations help keep sc2sea running! All donations go towards helping our site run including our monthly server hosting fees and sc2sea sponsored community tournaments we host. Find out more here.