The speed is decent. If you use WEP encoding or other security features, outsiders will not be able to access your network without a password / code key.
I have two wireless units in the house (3rd floor and 1st floor) and I wander around using my laptop where ever I want including on the patio in summer (and even the park across the street if I want).
Also, important to note that it is better to get a card like this for the PCs:
http://www.linksys.com/servlet/Satel...VisitorWrapper
rather than using the USB adapters (speed issues).
Alex