Can't connect to wireless network

[Mektarus]

HELP! I am a novice when it comes to networking and could really use some help. I have a Siemens SpeedStream 2624 wireless router which is connected by CAT5 cable to my primary computer which is running XP. I have an older computer running '98SE that has a D-Link DWL-520+ installed. When I first installed the wireless NIC it instantly connected to the network and I was able to use the internet. However, at some point, for no apparent reason, it simply stopped connecting. I have tried resetting the router. I have updated drivers for both components and firmware for the router. I've tried changing channels on both components. I tried assigning a permanent IP address to the computer with the wireless NIC and then adding the address manually to the network but the network wouldn't recognize the address. Both components seem to be working independently but will not communicate. Can anyone offer any assistance!:disgust: