(Win ME = Millennium Edition. It was the successor to Win 98. It went out of fashion about 5 years ago, I think)
I've been doing some more playing about on the HP website and come up with this:-
Go to
http://www.hp.com/cgi-bin/hpsupport/index.pl and click on the map (presumably the Europe bit and then the UK!)
Then click on the purple / blue box headed Product Support & Troubleshooting and enter your product name (Deskjet 1400 or whatever) in the box. This will come up with a choice of 3 models (1402, 1410 and 1417) so select the one that is yours.
At the next screen click on Getting Started, then Install Software and Drivers and the same again in the next window (!)
Then at the next window, choose Microsoft Windows (obviously!) and then from the list of choices, select "Windows - How to get HP Solution Center"
Click on the "+" sign to expand Windows Vista and then select the "Option two - Download and install ... from the website"
Follow your nose through the procedure and you should find that you'll eventually have "HP solution center" installed.
Then have a couple of paracetamol and a hot water bottle on your stiff neck and you should be in business!
Also, if you explore the website (makes you wonder who spends their days writing these websites, doesn't it?) you'll see other options for scanning from Windows Gallery and Paint - both of which work but maybe aren't quite as convenient as "Solution Center".