Debian Tip: How to Backup Installed Package List Before Reinstall/Upgrade
Many thanks to Renato for the following useful tip:
On your existing box:
COLUMNS=180 dpkg -l | awk '{print $2}' | xargs > /tmp/t
Then (having backed up then restored the list to /tmp/t, on the new install:
apt-get install `cat /tmp/t`