Hi,
So I bought a used laptop: it's a Latitude D505 with XP.
When I try to connect to my wireless internet, which works on my other DELL computer, the symbol in the task bar that it has an excellent connection.
However, when I go into Internet Explorer, it says that I am not connected to the internet.
I tried right-clicking on the wireless internet symbol and clicking repair, and it said that it could not renew my IP address.
What do I do to connect to my internet? Please help! Thank you! :]

Sounds like an encryption issue rather than anything else.
Also check to make sure you wireless adapter is DHCP enabled.

How do I do that? I'm not very good with computers...

IF DHCP enabled, check your router too and see if it will dynamically issue more than 1 IP address. By default the router will issue at least 50 addresses. Also, check to see that you do have a connection by the router. There is a tab on the router's page that allows you to see actual connections of computers connected.

How do I get to the router's page?
I'm sorry, but I'm completely computer illiterate

The router usually is at address 192.168.1.1... open a browser and type this in and see if you can get into the router software portal... the id is usually admin with a password of blank.

Did it work?

Yes, it did work, and the DHCP is enabled, but it still does not work

Click on Start, Control Panel and look for Dell Wireless Utilities. At the top of the settings in the Wireless Networks tab, you will see a checkbox for Let this tool manage your wireless settings. Is this, checked? If it is, the Windows Wireless Network Configuration Wizard is NOT in control of your wireless adapter. You will need to use the Dell utility to connect to your wireless networks. Look in the Link Status tab for more information regarding yor connection.

If you have previous connections in the list of Preferred Networks, delete them all so that you will know if your wireless card is connecting to your connection and not trying to connect to someone else's.