I'm planning to write/code one such stealth keylogger that would bypass detection by a certain antivirus. (I don't want to name the vendor as I know how good Google queries are against StackExchange websites).

I don't want to just download any keylogger from internet and try to encode it to evade detection. Writing code myself I would have the ability to make changes as I go; obscuration on both high-level and low-level language. I like control too.

It seems naive but is it true that keyloggers are a thing of the past, probably because of how effective AV's have become in detecting such programs?

I want some nice points on how can one easily write a robust, effective key logger preferably for a Windows environment?