You can use ExpertGPS to convert between many different coordinate formats, datums, and file formats. In all cases, this is a 3-step process:
1. Bring data into ExpertGPS (File/Import, GPS/Receive from GPS, Edit/Paste, or Tools/Add Waypoint).
2. Switch coordinate formats or datums (Edit/Preferences/My Coordinate Formats).
3. Output your converted data (File/Export, GPS/Send to GPS, Edit/Copy).
You need to understand how ExpertGPS works with coordinate formats and datums before converting your data. ExpertGPS lets you maintain a list of the coordinate formats and datums you use on a regular basis. You maintain this list by clicking Preferences on the Edit menu, and clicking on the My Coordinate Formats tab. Only one coordinate format can be active at a time - this format is highlighted in the My Coordinate Formats list. You can change the active format at any time by clicking in the list, or by clicking its name in the lower right corner of the main ExpertGPS window. In addition, any dialog where you are importing or adding data has a popup list so you can see or change the active coordinate format. Changing the active coordinate format will instantly reproject all of your data to the new format. Any data you export will use the currently active format and datum.
When you import or add data to ExpertGPS, you need to select the coordinate format and datum that matches the data you are adding. If the data appears in the wrong location on the map, click Undo, and double-check your coordinate format settings when re-importing.
Before exporting your data, switch to the correct output datum and coordinate format, either in the My Coordinate Formats dialog, or by clicking the coordinate format selector in the lower right corner.
Click Export on the File menu, and change the file type in the export dialog box. If you are exporting to Excel, you can use File/Export to create .csv files, or simply copy and paste from the list to your spreadsheet.
Once you have the coordinate formats and datums you commonly use added to ExpertGPS, you can use ExpertGPS to reproject coordinates, convert between file formats, and upload and download converted data to and from your GPS receiver.