You don’t need to fear the Internet if you just have the right knowledge and good judgments.
By the way you still need to update your system thru Microsoft service-update to have a nice and smooth system so you will need Internet at some point.
You can disable the “Local Area Connections” very simple thru just a mouse click in the computer. Then you only being online for updates and activations when you want. Its the same as you physical remove the cable.
If you not engage in porn surfing and that kind of activity its pretty safe even with out any virus program. 
A great virus program without any bad impact of the computer working with music programs are Microsoft Security Essential.
Microsoft Security Essential are 100% free too and very strong protections.
IF I were a MAC user I would be more concern and worried about security risk. Because of very little virus on OSX —>because of small global market share on only 5% on desktop, they users living in “dream world” that their computer are all safe.
Its just the opposite. In fact its open like a book and very easy to hack and take over and steal files. Same with IPhone.
You only need the IP address or more less the phone number of Iphone and you are “in-hacked”, no protections at all.
You can then take, listen, steal files, photos what ever from the Apple device.
PC has much stronger protections because of the long going security problems like virus and Trojans that made the overall OS much stronger and safer thru the years.
Best Regards
Freddie