The SD card doesn't change the firmware limits of 2000 geocaches and/or 200 GPX files. The SD card does allow for storing additional maps on that won't fit into the internal memory. You can get maps from sources other than Garmin and by placing them on the SD card you can expand the capabilities of your GPSr. I also use my SD card for storing geocaches to virtually expand the limits of the GPSr. The GPSr will load GPX files in the /Garmin/GPX folder on the GPSr or on the SD card. I do not place any GPX files on the GPSr itself, and store all of them on my SD card. I place about 9000 geocaches split across about 50 different GPX files on my SD card, and using my PDA, I move files into the /Garmin/GPX folder based on where I happen to be caching. THis allows me to essentially have access to all 9000 geocaches by moving a few GPX files around.
As for the compass, you should re-calibrate the compass after every battery change. I have not had near as many problems with the compass in my Oregon as I had with the one in my Colorado. On my Colorado, I would have to re-calibrate the compass after almost every cache find. With my Oregon, I have ony calibrated it once in the 3-4 weeks I've had it.
Thats clever Geekboy. I could do the same but would have to use my laptop to move the files. I take it your PDA has a usb port? It seems like I'm recalibrating with every cache. I am definitely talking to Garmin about this.