The challenge of all challenges...

[Professor_Adam]

Creationstory,
Yes that post is good. However, there is only one minor change that just happened two months ago. The Army recently changed RCP for SSG to 23 years (up from 22) and SFC went up as well. Just wanted to clarify that.
I work in retention so we deal with this all the time. When a Soldier decides reenlist "indefinite" it brings their ETS out to their RCP date. For instance, a SSG with 15 years of service who reenlists indefinite will have a new ETS that would put him at 23 years of service.
However, you can still request retirement at 20 years. Many of my friends have been held over though another year or two since the Iraq war began. I have seen very few SSG or SFC getting out at exactly 20 years now but that will likely change as Iraq is drawn down.