Here are two that I know work, we used them in the past:
These are AGP cards, not sure if you need the PCI Express or AGP.
http://www.newegg.com/Product/Produc...SubCategory=48
Here is a PCI Express that Should work:
http://www.newegg.com/Product/Produc...82E16814102006
Here is the Current PCI Express card we use it says that it is low profile, I am guessing you would need anohter back plate for any of these cards to make it "Low Profile"
http://www.newegg.com/Product/Produc...82E16814121537
Hope this helps.