Hi. I use Avira, have for years, pretty sure they still work under XP.
However, I have actually started using all My WinXP / Vista / 7 systems (I bought from Craigslist a lot when $ was better, planning to rebuild for young teens to learn with like i did) OFFLINE ONLY while using Windows.
I was able to still use these systems online for modern websites by running them under a bootable linux OS, which also allows Me to use the newest USB devices & harddrives with newer formatting technologies on the same systems as the XP / Other Windows for transferring files between modern & older systems.
The fact that I use a linux bootable OS also means that the Windows viruses out now are ineffective to these systems, & since I can use these bootable files either from a CDR or a USB flashdrive I can eliminate the problem of saved cookies & script remnants that backdoor future sites into a system.
And finally, to update the linux to a newer version I simply download the latest release & burn another 20 cent disc. Instant support for the latest browsers, email clients, & hardware versions, etc..