rsync-phenomenon

[August C. Quint]

Hi,

I have some questions regarding rsync.

I've created a little script that makes a backup of my home-directory using 
rsync. When I call this script again _all files_ will be copied again.

What's wrong here?

My environment:

OS is Linux (SuSE 10.3)
I want to backup my internal disk to an external disk connected via eSATA.
The internal disk is ext3, the external disk is FAT32 (I want to use this disk 
also on my Notebook running WinXP, connected via USB).
I use rsync  version 2.6.9  protocol version 29
the external disk is mounted via 
     mount -t vfat -o uid=1000,gid=100 /dev/sdb1 /media/backup
This is the command in my script:
    rsync -auv --progress --modify-window=1  --exclude=\.*  
~/   /media/backup/Linux/USER

This works with the effect I described above.

A little modification:
    source is now:   ~/MP3
    destination is now :  /media/backup/Linux/USER/MP3
everything works. For the first time it copies all the files to the 
destination. When I start it again it builds the file-list and detects that 
it has nothing to do. Fine.
But why not in the case of my HOME-directory?

Any ideas?
Thanks.

AugustQ

PS: if this question is already solved and there is a description somewhere a 
link is sufficient.