Info and opinions on keyboard functions and selection

OK.  I'm a guitar player, but there are quite a few songs which call
for short passages of other instruments which I cannot play.  I
therefore wanted to find a keyboard into which I could program these
short (10-20 second) passages for playback as needed.  For example,
the short flute solo in Fool On The Hill by the Beatles.  The song
needs this solo.  I've bought a flute, but can't convince any friends
to learn it.  SO I want to buy a keyboard that will allow me to record
and store that passage, which could be played back when I need it with
a simple touch of a key.
I'd prefer this be a function of the keyboard rather than recorded to
a cd for playback, but if the consensus is that the keyboard is not
the right item, tell me so.  I do have some friends, and my wife, who
will play this keyboard otherwise, but this is my reason to want one.
What would this function be called when searching thru keyboard ads,
sequencing?  I don't play out professionally and don't intend to. 
I've found a number of keyboards used between $100-$200 which would
probably be sufficient, maybe a Roland D20 or (if I get very lucky
D50) in this price range, but I cannot tell if they'll do what I want.
 I'm not stuck on Roland either.  I can get a Yamaha psr 500 for about
$100.  And can you tell me the difference between the yamaha pss and
psr keyboards?
I will be running the keys thru my mixing board and power amp, so I
don't need anything self contained with speakers and would rather see
the speakers value spent on better keys.
Thanks for helping a newbie.

Jun