Wireless MAN product experiences?

We're looking to setup a point-to-point link between two buildings circa
1.5km apart.

Optical, RF, whatever. This would be in the Detroit metro area
(Southfield, actually) so snow is to be expected at least part of the
year. License-free would be ideal.

The devices, or at least the transcievers themselves if seperate, must
be weatherproof/ruggedized for outdoor use (obviously). One endpoint
will go on a one-story building, the other can either be placed inside
our 10th floor suite (about 140' up) and go through a green-tinted glass
window, or on the roof (250' up).

100mbps is ideal, although if it's significantly cheaper to drop to 10,
that might be an option. I was thinking that 54mbit 802.11g might be a
good price-performance mix, but I don't know of the other products
available out there.

Does anyone have experience with something like this? Should we try
using WiFi and directional antennas, or is that insane? What sort of
experience have you guys had with different vendors gear?

Please reply offlist and I'll summarize my findings to the list