Missing Wireless WLAN Driver

I have a Dell Inspiron 5100 Laptop and I recently upgraded from Windows XP Home Edition to Professional. Also, I installed a new hard drive as well. My old hard drive was a Toshiba MK6021GAS 60GB and my new one is a WD Scorpio 80GB. My old hard drive was warped (very old), however, before I changed out the old hard drive I installed XP Professional on it and the wireless network worked just fine. However my hard drive was warped and would not work properly, my computer would just shut down so I had to put in the new hard drive and reload XP Professional, and it loaded just fine. Now everything is working properly, only my wireless network is not being recognized, I went into the device manager and it is not even showing the 1400 TrueMobil Wireless WLAN driver. I know that I need to install the wireless network driver in order for it to work but what do I do if my OS is not even recognizing an internal wireless card. I know I have one because it is what I have been using up till now. HELP ME PLEASE!