A couple of questions about sparse images
 

I tried superduper for the first time last night. I backed up from my local 40GB HD to an image on an external USB HD. Since my laptop only has usb 1.1, I started the process and left for the night. It ended up taking over 10 hours.

When I woke up today I checked the computer and found the following. Superduper said the process had been completed succesfuly but the image size it was 26.2 GB, wich seemed rather small. I checked my local HD and saw I'm only using 27.3 GB, a bunch less than I thought (my 40 GB drive is actually 37, there goes 3 gigs!). Still, there's a 1GB difference. Is that because of the files omitted by superduper?

Also, I used the free version of superduper since I was just testing it. If I get the full version, can I do a smart update on the image I have now, wich was created with the "erase then copy" option? Is there's a difference in how "erase and copy" and "smart update" create images?

Yes, there could easily be a 1GB difference; swap files (VM) which can be quite large are excluded.

You can definitely Smart Update an image created when you're not registered.

Great, thanks! :) I registered this morning, and so far it's worth every cent.

Thanks; I'm glad you like it!