If you still insist on using your Windows 7 computer and are scared of using it thanks to Microsoft's lack of continued support, it is still okay to use it offline. If you don't take it on the internet, you significantly lower your risks to catch anything harmful for the PC. Plus, most of your permanent applications will still work as long as there is electricity to power the computer! However, you should still be sure to back up important files onto an external hard drive, as staying offline means no access to cloud backup services. If you need to get online for anything, use another (connected) device, just don't give in to the temptation while on Windows 7!