HP also has ES1000 cards as well. You may be able to run the HP install on the Dell
Just download:
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=15351&prodSeriesId=1121516&prodNameId=3288134&swEnvOID=4024&swLang=8&mode=2&taskId=135&swItem=MTX-453dbf1a3f79443aade02849f5
The install may work. If not, extract and try and update the driver from the device manager and browse to the folder where you extracted the files and it may pick up the drivers.