I've Fixed It!
For anyone with similar issues:
So actually quite easy to fix. The modem came with my Packard Bell PC when I bought it. So I went to their website, found the support page, downloaded the driver setup file.
Then, before instaling the driver I right-mouse-clicked on the downloaded file and went to "Compatibility", I chose "XP Service Pack 3" and then ran the file.
Worked a treat. Will now try the same on my webcam driver
So here's a question for Microsoft - you're quite a clever company, you even provide a nice little program to pre-test our existing XP systems for compatibility issues (even though some of the links offered as fixes for non-compatible drivers took me to NEC's Japanese-only hiome page...). Why not then have a that little program do something like.... say....
"ah ha... we can tell that your modem driver only works with XP... we'll put that (and any other similar XP-only drivers) into a little batch file.... then we'll call that file during Win 7 installation and ensure the drivers are installed for you in compat. mode..."
Hey presto. Hmmmmm...... look., look... flying pigs....
By the way. Having installed 7 I'd like someone to tell me why I did. Because apart from shutting down being a lot quicker, I'm not sure I can see any real difference with XP other than cosmetically.