If it's not localized to your computer, no I don't think ESET is the problem. If it works for you, leave it be.
What is your wireless modem model?
I know that I used to get really slow speeds when my kids were watching netflix before we upgraded to 12MBs, but our lines were also overloaded at the time.
When your wife is not watching Netflix. Go to
www.speedtest.net and run a simple speed test. You should be getting around 5 MBs. If you aren't, I'd try contacting your ISP and complaining about the actual speed vs what you are paying for. If it's fine. You maight want to get a dedicated wireless router from best buy or someplace like newegg.com. Connect this to your modem directly, then run wireless from the new router. The dedicated router should be able to route traffic more efficiently and do some load balancing for you so that your wife can watch Netflix and you can use the internet at the same time.