I assume you're talking about the original Screamer (there was a
Screamer II that came out in the mid-90's - definitely an upgrade over
the original). The original Screamer was a late 80's design. Worked
great at the time - it and the Sunset Slalom were the standards of the
day, and zillions of people have fond memories of them.
While it was a great board at the time (very reasonable compromise of
speed, acceleration, easy jibing, and friendly ride), that niche
(freeride boards around 100 liters) has evolved dramatically. Anything
you can find from, say, the mid-90's on in that group (such as the
aforementioned Screamer II) will, for one, work better with today's
rigs (that's because the very forward mast base on the original will
make it hard to trim out a modern sail on it). And in terms of
performance and usability, the more modern boards will simply blow the
old one out of the water as soon as you're dealing with more than just
a ripple on the water (in dead flat water, that old Screamer will be
remarkably good still).
Don't know what kind of deal you're getting on it. I'd just suggest
that for a few hundred dollars, you'll be able to find something much
more recent, with higher performance and better construction (if that
Screamer has seen even occasional continued use over its life, it must
be getting pretty soft by now). Browse the online classifieds and see
what's out there. A Screamer II or F2 Ride 278 (both just over 100
liters) will be good candidates; a Bic Techno 273 should also fit the
bill. Starboard Carves around 100 liters, if you're going for something
a little more recent.
Andreas