The first related to the printer. Initially I was happy that I had been able to print to our existing printer from the new computer as soon as I connected it, without a need to look for drivers or to run an installation process. It's not a network printer, but so the long as the computer that it's attached to is switched on and sharing is enabled, other computers on the network ought to be able to print on it. And that's how it used to be. But, try as I might, I couldn't print from other computers via the new computer.
To cut a long story short, the issue turns out to have been that the new computer runs a version of Windows 7 (64 bit) that isn't compatible in certain respects with the versions that the other computers use (32 bit). Hence, a 32 bit driver had to be installed on the new computer. Just as well I'd found the original CD with the drivers on it, because there was no way that the new computer could be persuaded to install the necessary drivers from the internet (the wizards are all about getting newer versions, not older ones). And, no, it was no use installing either the new or old drivers on the other computers..... I tried every possible combination (and quite few other things, such as double-checking all the "sharing" settings) before I stumbled on the approach that finally worked. By the time I had googled for the solution, checked out numerous false leads and so on, this little exercise took more than 3 hours!
The second issue related to getting sound from the new computer. It clearly didn't have a speaker built into it, yet when I plugged external speakers in, nothing happened (edit - and the speakers in the monitor didn't work, either) .
This time, as a result of googling, I was led to the Microsoft "Fix It Solution" centre - and almost unbelievably, the downloaded problem finding application identified the issue straight away (which I think was that the new computer hadn't managed to identify the not-very-new generic speakers that I'd plugged in), and actually managed to get the sound working. Total time - less than an hour (most of which was taken attempting to adjust the various "sound" settings before resorting to google). It's nice to know that Microsoft can sometimes actually come up with something that's helpful (instead of just stating the obvious and/or platitudes).