I used
Norton Security v22.15.x (Norton's legacy version for Win XP and Vista) on my Vista SP2 machine until 2019 when I purchased a Win 10 laptop. I would purchase a spare Norton 360 product key on sale at a local retailer like Staples or Best Buy and keep it on hand until my annual subscription needed to be renewed, and never paid more than $21.99 CAD (~$16 USD) for a 1-Year 5-device license. I personally felt that Norton was a much better choice for me than the legacy AVG Free v18.8 because Norton had advanced protection features (e.g., anti-exploit, anti-ransomware, Intrusion Prevention, etc.), still received vulnerability updates and compatibility fixes described in the Jan 2022 support article
Maintenance Mode for Windows XP, Windows Vista, and Windows 7 SP0 for Norton Security Software (e.g., for an updated Intrusion Prevention engine IPSEng32.dll), and came with a top-notch Norton Smart Firewall. The current product update for the legacy version of Norton is
v22.15.5.0 (rel. 24-Sep-2020) and if I were still using this legacy product I wouldn't be overly concerned that there hasn't been a product update in a few years, given that the Win XP and Vista operating systems are unsupported and no longer undergo major changes, while the "regular" Norton v22.22.x products for Win 7 SP1 and higher receive regular updates for OS changes (e.g., Win 11 v22H2 compatibility) and new "bells and whistles" like Norton Smart Scan, Norton Software Updater, Norton Crypto (thankfully discontinued in Sept 2022) and other bloat that many Norton 360 users neither need nor want.
Current Norton 360 licenses are multi-device (PC, Mac, mobile devices) and normally allow installation on 3 to 5 (Deluxe license) or 10 (Premium license) devices, so if you own more than one device like wither3 and already use Norton 360 v22.22.x on your newer devices then you can install the legacy version of Norton v22.15.x on your Win XP or Vista machines at no extra cost.
I currently use Microsoft Defender as the main antivirus on my
Win 10 laptop but also run Malwarebytes Premium v4.5.x in real-time protection mode. I have turned OFF the Malwarebytes setting at Settings | Security | Windows Security Center | Always Register Malwarebytes in the Windows Security Center, which ensures that Microsoft Defender (or whatever third-party antivirus you prefer to use) is registered with Windows as my main real-time antivirus and has the primary responsibility for malware detection and remediation, while Malwarebytes Premium will essentially work as a "backup" to look for any potential threats missed by my antivirus. I purchased a few lifetime (perpetual) licenses for Malwarebytes Premium several years ago (sadly, Malwarebytes stopped selling these lifetime licenses in March 2014) so there is no extra cost to run Malwarebytes Premium on my Win 10 laptop
I rarely boot up my old
Vista SP2 laptop these days and didn't see the need to continue paying ~ $20 for an annual Norton 360 license - other than Norton VPN, most of the features that Norton has added to their Norton 360 product line in recent years is useless bloat so I don't feel I need Norton 360 on my Win 10 laptop. I currently use
Malwarebytes Premium v3.5.1 (the legacy version for Win XP and Vista) for real-time protection on my Vista SP2 laptop, and this is another lifetime license so I don't have to pay an annual fee to use this product. If this Vista SP2 machine is booted up I will briefly connect to the internet to update the Malwarebytes malware protection definitions (i.e., virus definitions, web protection, anti-exploit, etc.) and then disconnect again.
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32-bit Vista Home Premium SP2 * Firefox ESR v52.9.0 * Malwarebytes Premium v3.5.1.2522-1.0.365
HP Pavilion dv6835ca, Intel Core2Duo T5550 @ 1.83 GHz, 3 GB RAM, 256 GB WD SATA HDD, NVIDIA GeForce 8400M GS
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64-bit Win 10 Pro v22H2 build 19045.2251 * Firefox v108.0.0 * Microsoft Defender v4.18.2211.5-1.1.19900.2 * Malwarebytes Premium v4.5.19.229-1.0.1860
Dell Inspiron 15 5584, Intel i5-8265U CPU, 8 GB RAM, 256 GB Toshiba KBG40ZNS256G NVMe SSD, Intel UHD Graphics 620