Which files to backup?

[BGP]

I move my GC files between to 2 computers so I can work on them at the 
office and home.

The only files I back up are  a couple of recent XAC files, some recent 
LOG files and the big Gzip file located located in some folder by the 
same name.


I've had no problems in moving between 2 computers and all of the data 
appears correctly.


Is what I'm doing sufficient for backing up my data?  Or, is there 
something else I should include?