A couple of options, depending upon how cheap you are and how well you would like the GPS program to integrate with Excel.
Microsoft Streets and Trips - really cheap ($35 or $65). Option to purchase a bundle that includes a
USB GPS receiver or just the software only and use your own GPS receiver.
Pro: You can import waypoints from an Excel spreadsheet.
Con: You can't go the other direction.
Microsoft MapPoint - More expensive ($269). Software only. You have to supply your own GPS receiver (not necessarily a bad thing).
Pro: You can integrate Mappoint with MS Office very tightly, including using maps in Powerpoint and Excel charts. You can go both directions (import/export) with data in an Excel spreadsheet.
The reason I suggest that buying a seperate GPS receiver isn't such a bad thing is my bias about the best type of receiver to use with a laptop. I have two USB receivers and two Bluetooth (wireless) receivers. I much prefer the Bluetooth receivers because there is no restriction on where I place the receiver in relation to the laptop. I can place both in the optimum locations without any concern for a cable between them.
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