"The laptop keeps retriving a different IP than the PC's"
Thats how it should be otherwise if you had you're other PC on at the same time the network would not be able to identify each one.
"The voyager keeps telling me there is encrytped security"
Have you enabled encryption on your wireless network? You need to input the correct encryption key into your laptop so that it can connect with the wireless network.
A way to get it all operating would be go into the routers setup and turn off encryption and then get your laptop to connect once you have that up and working re-enable encryption and enter the key into the laptop. This is done from the network connections in the control panel. Find your wireless connection right click | properties | wireless network tab | click on your network and choose properties and then enter the network key. Thats under XP