I have no idea what an "Apples Time Capsule" is, but your present
upgrading is likely trying to download a humongous amount of programs
and data, and the 10 hours sounds about right for a DSL connection.

As I recall from April of this year when my 7.10 system auto-upgraded
to 8.04, it downloaded some 600 to 700MB (perhaps more) of stuff to
do that upgrade. At that time I had a 6Mbps broadband connection to
the 'Net and it didn't take too long but I didn't time it -- I just
fixed dinner and watched a movie and let the upgrade run and it was
finished when the movie was over, so it took less than 3 hours for
the downloads and the upgrade install.