Windows XP having trouble aquiring an IP from wireless router

Hi. Hopefully someone has an idea about how to fix this because I've run out of them. This is the situation:

I have a home network set up with Verizon FIOS has my ISP. The modem Verizon gave us is a Actiontec MI424WR which has a wireless router built into it. There are normally two computers connected to this: one a desktop with XP connected via CAT5 and the other a laptop with Vista connected via wireless though there have been several other laptops connected wirelessly over the past 2 years. My problem is this:


I wanted to connect my old windows XP sp1 desktop to the network via wireless but I've been having trouble. It can see the wireless network and says it connects but when it does it refuses to acquire and IP address, DNS address, ect from the router so it just sits there saying it's connected but it can't connect to the internet. I know I have the correct WEP key entered so I'm not sure why this is.

My only attempt to circumvent this was to enter the IP address, gateway address, and DNS address manually (In network connections -> wireless card -> properties -> Internet Protocol (Tcp/IP) -> properties ). Doing so allows me to connect to the internet but every 2.5 minutes on the 2.5 minutes the router disconnects me and I have to reconnect.

This is a basic overview, does anyone have any ideas?