In addition to Brett's comment:
If you don't actually need to create any of the data (either you're utilizing shapefiles, rasters, or you have axf files already created) you would not need ArcPad installed on your computer.
As long as you have ActiveSync installed (Windows XP) or Windows Mobile Device Center (Vista / 7) you can plug in the mobile device and transfer files to and from device.
But as Brett said, if you actually need to check out out data for editing (feature class to axf file) or create apm's, you would need to have ArcPad installed.