No expert by far, just a personal view:
Hopefully Groink's new LT has the Windows 8.1 installed , with a start button. Win 8 systems have a newer learning curve, takes a little time to get use too. Sometime older programs don't run well (or at all) in Win 8's.
And yes, the 8's have Defender installed , so in theory you need not have another virus program added (in theory). Just to note, having two, or more, anti virus programs installed will only slow the machine and give many, many false positives flags.
Linux, superior & faster OS, but if any one has only using Windows in the past, there will be needed a different approach to working with it. Linux based OP's are many, and most are free. But running a Win program, on a Linux system, can be a pain in the ass (wine, virtual, crossover, etc). Dual boot ups work well.
If your on the web, you will pickup a virus, malware, edtc...no doubt. Russian/China/India porn & torrent sites are noted for this. If government agencies/giant corps, spend millions almost every day developing anti virus, etc, still get them, so will you. Don't care what OP is run, that personal computer, lap top, tablet, etc is an easy mark for people who know what their doing.. Any anti virus program are no solid guarantee. Same can be said for IP/VPN/Firewall software, which most are usually slow and overrated. Apple people are still in their own dream world about getting a virus/malware....they do and will. Safest OS is probably a Linux/GNU run system.
Been told by people much smarter than me that sites like GB are a piece of cake when it comes to hacking. A couple of them are still in high school.
World War III will be a cyber war, doing much more damage that any bombing raid in all history ever though of doing. The inter structure, power grids, finance/banks,water systems, communications, etc can be destroyed without a shot being fired. China, perhaps, the main worry in the future.