I'm a newbie to boat electronics, so I'll apologize up front for some
basic questions.

I've got a 32' flybridge sedan that I use on Lake Lanier in Georgia
(lake is about 140 feet deep, max). I currently use a handheld Garmin
GPS 76 for navigating, an old Hummingbird fishfinder on the transom and
the original depthfinder on the flybridge (kind of a "Rube Goldberg
goes fishing" setup). It's time to replace the depthfinder and I'm
going to consolidate and upgrade to either a Garmin 178c or a Lowrance
332c. My greatest need is a good depthfinder / fishfinder component.
The GPS mapping feature is secondary (after all, I'm on a lake) - I
really only need guidance home when the rain and fog rolls in and I
can't see my landmarks. I favor the Lowrance based on the comments I've
read on the quality of the sounder and the availablity of Navionics
maps, but any thoughts you have would be appreciated.

Here's my real dilemma. I want to put the new GPS/sounder unit on the
flybridge and use my laptop on the lower station when the weather is
nasty.

1) Can I direct cable from the GPS/sounder to the laptop, or will I
need a multiplexer? I'm going to use an old IBM laptop that has two USB
and one 9-pin serial connections. Even if I can direct cable, will the
use of a multiplexer improve the ease of installation and/or the
stability of the connection?

2) Can the setup be configured for the laptop to function as a second
screen replicating the GPS/sounder screen (similar to adding a second
monitor to a computer)?

3) If the answer above to 2) is no, which PC-based chartplotting
program(s) will display the depth and speed from the sounder as an
overlay on the GPS navigation map on the laptop screen - or must I
toggle between two seperate screens on the laptop?

Thanks in advance for your help.