Does the Linksys router have a hardware firewall integrated? Most of the ones produced these days do. That should be a good front line defense against getting hacked directly.
For viruses and stuff, I'd avoid anything with McAfee or Norton in the name. Those programs are horrible about taking over your pc, almost acting like viruses themselves at times.
A good free virus scanner is
AVG
For free spyware scanning, I'd recommend
Lavasoft Ad-Aware and
Spybot Search & Destroy. Use a couple of them cause one doesn't always cover everything out there.
Leave the Windows Defender software firewall running and it should give a good software backup to the router.
Overall, the best advice is just to be aware of where you are surfing the web. Stay away from Sex and Warez sites. Don't ever open email attachments unless you know exactly what they are.