I wireless enabled a desktop PC for the first time just a couple of days ago.
I bought an internal PCI card for less than £20, took off the PC cover, and fitted the new card (very easy).
Upon restart it found the wi fi straight away and I was able to logon to my router.
Whole process took about 30 minutes.
This was the one I bought.
http://www.amazon.co....dapter/dp/B001811NCO/