Transferring GPS data
The objective here is to get data collected in a GPS into a format usable in GIS, typically a shapefile. Usually I try to keep the GPS data in a raw format, WGS84 latlon and then after I transfer it into the shapefile, I use ArcToolbox Project tool to put it into the format needed by the current project.
DNR Garmin extension
When I use a Garmin handheld for data collection, I use the DNR Garmin Extension program to import the data. It works quite well with ArcMap 8.x and 9.x. It will write shapefiles directly if you have ArcMap running but it can also run standalone and write text files if you don't.
DNR Garmin Extension and other potentially useful tools are available from http://www.dnr.state.mn.us/mis/gis/tools/arcview/extensions.html
A manual for DNR Garmin produced by Forest Service: ftp://ftp-fc.sc.egov.usda.gov/NCGC/products/gps/software/dnr-garmin5-arcmap.pdf
More options
I have used Garmin Mapsource to do data transfers. You can download data from a Garmin using Mapsource, then you can save the data out in DXF format. Then you can import the DXF data using ArcToolbox. I would not run out and buy a copy of Mapsource just to do transfers, DNR Garmin is far better and it is free.
GARNIX is a communication program that provides data interface between MS-DOS/Windows/Linux computers and a GARMIN GPS device
GPSBabel converts waypoints, tracks, and routes from one format to another, whether that format is a common mapping format like Delorme, Streets and Trips, or even a serial upload or download to a GPS unit such as those from Garmin and Magellan.
I have more details on how I use gpsbabel on my eMap page.
Windows
ArcMap extension for Garmin mxgeo (does not work on my computer) ($50 shareware)
Linux
gpsd data collector
