SMcNamara
On a related point, I have a USB wifi adapter that I would plug in, update and then "disconnect" from the System Tray icon.  Then unplug the USB adapter.  I sense I could go into the Device Manager, right-click and disable a USB port that the adapter sits in but how do I know which USB item in Device Manager would be correct?
 
Thanks,
 
Steve

In your case the quickest way to simply unplug the USB cable from your laptop. Then it will no longer appear in device manager anyway.
 
The other way is to right click and disable the adapter from:
Control Panel->Network and Internet->Network Connections
 
Ta,

Always offline. We have slow unreliable internet.
I download at work and take the files home on a thumb drive.

Doktor Avalanche

SMcNamara
On a related point, I have a USB wifi adapter that I would plug in, update and then "disconnect" from the System Tray icon.  Then unplug the USB adapter.  I sense I could go into the Device Manager, right-click and disable a USB port that the adapter sits in but how do I know which USB item in Device Manager would be correct? 
Thanks,
Steve

In your case the quickest way to simply unplug the USB cable from your laptop. Then it will no longer appear in device manager anyway.
The other way is to right click and disable the adapter from:
Control Panel->Network and Internet->Network Connections
Ta,

Thanks Doktor.

The only reason I would disconnect is if I had a slow system which needed all the clock cycles it could get. I have a reasonably beefy machine and have no trouble running Sonar, without glitches, with the firewall and Windows Defender running. This is with very heavy projects containing lots of CPU-hungry synths and effects. 
 
The only people I've ever heard express paranoia about being connected to the internet are music producers. I have no idea why this is. I get that some people like to stay disconnected to minimize performance issues, but look around, there's a whole world of tech and creative pros out there who rely on their systems to run all sorts of complex and powerful software, yet they stay online without issues. In most cases their jobs and businesses rely on it. Personally I like to think that with almost 20 years of internet experience under my belt, I've instinctively learned the do's and don'ts of online security. You can tell just by looking at my desktop, which has remained relatively free of flying toasters and dancing gorillas for at least 15 years 

One point I often make is being offline alone does not protect you from viruses. In a non music environment we had a situation where computers not connected were being infected from removable media. They were vulnerable as they were not receiving security patches and AV updates. This can be managed of course and you have to be very careful with thumb drives etc.

My DAW stays on line (ethernet) but just for updates etc. I have not noticed any performance issues. I use another PC for email, browsing and most downloads. Both have stayed uninfected. A third PC the grand kids use needs cleaning quite often. They click on anything. I suspect links in social media for most of it.

Your router is the front line of defence, as long as you have the security set up it will block most intrusion attempts. If you log in to the router and view the logs you will probably see evidence of attempted intrusions.

The problem is not only that you can catch a virus. The real problem these day's is the increase of ransom-ware. Imagine your costumer comes by to see (or better - hear) how things are progressing, but you can't do anything because all your data is encrypted and thus unreadable - Including all your costumer's data. You have to pay (most times in bit coin) to get your stuff unlocked again.
 
It does not hurt to be on the safe side of things. It is not really paranoia to restrict Internet access. There are really people out there that want to get into your computer. They are not interested what is in your data (mostly). They only want to strip you of your money.

JClosed
The problem is not only that you can catch a virus. The real problem these day's is the increase of ransom-ware. Imagine your costumer comes by to see (or better - hear) how things are progressing, but you can't do anything because all your data is encrypted and thus unreadable - Including all your costumer's data. You have to pay (most times in bit coin) to get your stuff unlocked again.
 
It does not hurt to be on the safe side of things. It is not really paranoia to restrict Internet access. There are really people out there that want to get into your computer. They are not interested what is in your data (mostly). They only want to strip you of your money.

That's just spreading paranoia imho. Just buy a decent antivirus and make sure your firewall precautions work, and patch your machine.

SMcNamara
On a related point, I have a USB wifi adapter that I would plug in, update and then "disconnect" from the System Tray icon.  Then unplug the USB adapter.  I sense I could go into the Device Manager, right-click and disable a USB port that the adapter sits in but how do I know which USB item in Device Manager would be correct?

In Device Manager you don't need to disable the USB port. The network adaptor will have an entry of its own and that's the one to disable. Simply unplugging it won't necessarily result in the driver being unloaded or stop it trying to poll the (missing) interface.

On the subject of wifi network adaptors, they're notorious for causing problems in Windows DAWs and video editing workstations. Surely there must be at least one company that can turn out an interface and driver that doesn't hog the PCI bus, or MS could fix the problem if it's Windows fault.

Apple use intel hardware but OS X doesn't have the wifi dpc latency problem at all and never has. I'm tempted to use bootcamp to put Windows on one of our Macs just to see if the problem is there when Windows is running on Apple hardware and using Apple-supplied drivers.

nearly 90% of PCs run Windows so it makes most sense for the bad guys to concentrate on breaking into Windows machines.

 
Possibly, but the proportion of PC's connecting to the internet is now very small compared to ten years ago. Windows PC's used to account for 95% of all machines connecting to the internet. I read that's down to around 15% these days, with everyone using their phones and tablets to surf etc. Would it then follow that Windows DAW's are less likely to encounter problems?