Wireless disconnects

I am new to Macs and my white Macbook (January 09 revision) with Leopard 10.5.6 and all updates has been dropping its internet connection recently. It has worked fine for the past two months, but this week the computer fails to connect and get an IP address to wireless routers. This issue happens both at my school and home, so I don't think that it is the environment because there are wireless devices that connect without a problem in both places. I have to remove the network from the list in network preferences, turn off airport, and turn it back on to get the wireless to connect.

Is anyone else having this issue or do you have a solution?????

You will probably find it more reliable to set up 2 Locations in your Macbook, one for school and one for home and enter DNS settings etc in each of the locations.