Dennis,
Congratulations! I just bought a home as well. I don't have my stereo in the garage (at least it hasn't been pushed there yet!), but depending on where you live I might be concerned about temperature/humidity changes. I know my garage here gets very cold in the winter and very warm/humid in the summer. Not sure what gear you have either, but more sensitive gear might not like those conditions. I also have a bad habit of leaving the garage door open when we're home but not using the garage, and I'd hate to have thousands $$ of equipment(or tens of thousands? depends on what you've got) sitting out there in the open.
-Eric B.