nice output functionality with screen (eg. w/ "less" pager)

[Zenaan Harkness]

I very much like how when I use "less" in screen, the output goes
straight into the terminal's buffer - perhaps this is one of those
.screenrc options I set, but the point is, this doesn't happen with
xterm:

with xterm, if I use less, it blanks the screen, and asks me to press a
key to end. When I press a key, whatever was on the screen before
returns, and the output from less disappears.

A similar thing occurs with vim.

Does someone know why this is?

Does anyone know how to make xterm behave in this nice way?

tia
zen