you can try to do an exact clone of the sd. On your n900 do
sudo su then dd if=/dev/mmcblk1 of=/home/user/MyDocs/sd_backup.img bs=100M

I am not very sure about the "bs=100M" I usually just run it without it. However, some ppl say it's faster when you have a value there.

16GB gonna take some time to finish so be patient