PostgreSQL with PostGIS on embedded hardware

Hi all,
recently I came across a question from a customer of mine, asking me if
it would feasible to run PostgreSQL along with PostGIS on embedded hardware.
They didn't give me complete information, but it should be some kind of
industrial PC with a 600MHz CPU. Memory should be not huge nor small,
maybe a couple of GBytes, hard disk should be some type of industrial
Compact Flash of maybe 16 GBytes.

They are thinking about using this setup on-board of public buses and
trams, along with a GPS receiver, for self-localization. So that when
the bus or tram enters defined zones or passes near defined points,
events are triggered.
The database could probably be used completely read-only or almost that.

What performances do you think would be possible for PostgreSQL+PostGIS
on such hardware???

Bye
Paolo