Moving Unstable to new HDD

[KS <lists04@fastmail.fm>]

Hello all,

I have a 80GB+40GB pair of HDDs in my desktop. The 40GB is the one which
came with the system and contains the original Windows installation. The
 80GB hard disk contains the Debian unstable system with different
partitions for /, /boot, /usr, /home, /tmp, /var and a couple of others
for data storage.

I have ordered a 320GB SATA disk (along with a Promise controller card)
and intend to move the Debian system to it (while keeping the 40GB as it
is). Just redoing the installation on the new HDD is a possibility but I
was wondering what other options are there to archive the goal. If I use
dd, can I have the new partition size larger than the original one or
does it have to stay same? What would be best way to move the system to
the larger HDD and also have bigger /usr and /home partitions?

Thanks,
KS.