I just reinstalled windows xp and when everything

Click on the link below

http://gd.panam.acer.com/home/

Choose notebook -> Aspire -> 5100 Series

This will give a list of drivers you will have to install after an OS reinstall.

Choose the wireless LAN as you scroll down the list.

Choose either Atheros or Broadcomm depending upon which wireless card is installed in the system.

Then install the software. Restart the system.

Choose the wireless network you would like to connect to and then enter the pass key if asked for. This can help you connect to internet wirelessly.

Regards,
Sai

Download the drivers from the Acer WEB site Make sure you select the model of your laptop and the XP version of the drivers you that require matches the Windows version that is installed on your laptop. Use this link to get to the Acer support: -
http://www.acersupport.com/notebook/index.html