GPS coords difference

Hi all,
when entering these coords into (for example) MapQuest:

51,05097 N
3,36368 E

I get a (?correct address)

When entering the same coords in MP2004, I get an address some 15 miles away.
What's causing this? Who can help me out.
As far as I know, MP uses WGS84, and so do the devices giving me the original coords.

Any suggestions?

James

Look at this thread - It might help. There is a link from Eric that looks good.

GPS Longitude and Latitude does not agree with MapPoint
http://mp2kmag.com/mappoint/discussion/viewtopic.asp?t=5263&highlight=wgs84