Hi mikeraj,
You may replace the Dell WLAN 1703 card with a Dell WLAN 1525 card.
Please refer to the Owner’s Manual link: http://bit.ly/16u6QQt, to check how to remove the WLAN card from XPS 9100.
Please refer to the Owner’s Manual link: http://bit.ly/YLvdIh, to check how to remove dell WLAN 1703 out of XPS 8500 and how to insert Dell WLAN 1525 card.
Please share the operating system with me to provide you with the correct drivers that are required to install Dell WLAN 1525 card on XPS 8500.
Hope this helps. Please reply with the findings.