Depends on how old it is.
Junk for me is anything over 3 years old, unless it's a server - some I have are getting on to 5 years old. Stuff to sell is anything beyond 6 months to 3 years.
I also don't use anything which is cosmetically damaged - e.g. a dropped laptop, etc even if it's fully functional - it's bad for my image. They get sold / given away, regardless of their age.
Some things which I'm not using but anticipate needing in the near future get stored. I try and avoid doing this because with all the office moves of late, I tend to forget about stuff.