If your computer is old, and doesn't have a USB port, then you can get cards to slot onto your motherboard (if you have a spare slot on your motherboard.)
Here is a quick link to illustrate the type of thing available.
http://www.nisis.com/Products/PCComp.../ComboCard.asp
(You may be able to do better than the quick site I found to illustrate the point.
I hope that helps)