Oh, I forgot about the modem. Yes, you can connect the modem again and use the internet on other computers, but don't connect the infected one to the internet yet. And yes, you should go to Control Panel and remove any suspicious programs installed today. If you want to know how I would proceed on to clean the PC you can go to the "Steps" part of this post.
Norton is right and not right at the same time when they say it is not possible to infect the DSL modem and/or wireless connections. It's not impossible, it just requires a real whole lot of work because the malware running from the computer would have to identify the software running on the modem before trying to infect it and have a piece of software that can run under the found modem's architecture.
As you can see, it is very unlikely (but not impossible) for that to happen for there exist so many modems running different kinds of software. It would be one hell of a malware to infect a modem, if it would I would personally get on a plane, go to your home and get a sample of that malware to study it.
But jokes aside, a more possible scenario is that the malware scans your local area network for vulnerable computers and try to infect the other computers if it finds an opening. But let's not worry about that because we are about to kick out whatever malware has been bothering you before they have a chance to do anything big.
[Steps]
First, do run Norton Power Eraser. Let it find and remove whatever it detects as malware. You will probably have to restart the computer before everything is done. Finish this before going to "Second".
Second, Go to Control Panel and try to find what programs were installed today by sorting them by date. Usually there is a column that says "Installed On" from which you can sort the installed programs by date. From those, try to identify anything suspicious. Anything suspicious would be something you have no memory of having installed yourself. Also, if you find something from VSupport installed, uninstall it (for you no longer need their support). If VSupport was legit, everything should proceed smoothly. Otherwise, either you will have trouble uninstalling it or it will appear to have been uninstalled, but it would still lurk hidden on your system.
Norton Power Eraser should do the whole trick and even remove anything from VSupport if it was actually unlegit and malware so no further action would be needed. However, if you really really want to take it a step further (I don't think it is necessary), you can proceed to "Third". "Third" is just a way to make sure you get everything from VSupport removed from your PC in the case Norton didn't detect it as a potential threat but as a legit set of programs or to have other hidden entries in your system that are hindrances removed from it.
[Optional]
Third, to identify any misbehaving programs that may still be hiding from you and Norton Power Eraser I suggest to try
HijackThis. Free open source program I always use to manually get those pesky programs that like to misbehave. You can follow
this tutorial on how to use it. Just until the part of
How to restore items mistakenly deleted. To be on the safe side, create a system restore point before using HijackThis.
If HijackThis is too much of a bother, you can always use the free edition of the software
Spybot which will make pretty much the same thing Norton Power Eraser did to have things nearly automatically done (you still have to choose what to remove and whatnot but in a more user friendly interface than that of HijackThis).
Sorry for the long post. I expect to have covered the best way of cleaning your PC from threats, but it is important to know that other people would use other methods. Also it is important to know that different kind of infections and different kinds of computer behaviours call for different methods. I personally would proceed like this in your case.