Hybrid Bicycles - Trek 7.3 FX + Trails

I've read that this bike is no good for trail riding such as logging roads and also a store salesperson told me this. Why is that?

I read an article a guy wrote a number of years ago and he actually won mountainbike races using a road bike.

What would be so bad about taking a bike like the 7.3 FX on trails?

I want a road/trail bike, but I want one that leans more towards the road bike side.

I'd swap out the slick road tyres for some fast rolling CX tyres and make sure the wheel build was 110 %... then it would be nice on trails and still pretty decent on the road.

Some folks might think that because a bike does not have a front suspension that it is not trail worthy... lots of folks ride rigid mountain bikes.

Is a 7.3 FX a good choice then for what I'm looking for? (a road/trail bike that leans more towards the road side).

Or should I be looking at something totally different?

I'm just trying to keep the bike as light and fast as possible without getting a bike that will break if it hits a pothole on a logging road or get flats easily.

I was thinking a cyclocross tire also; I've seen some the exact same size as the FX tire, 700 x 32.

The 7.3fx is exactly what you describe you need: a hybrid road/trail bike that leans more towards roads.
As Sixtyfiver said: get some CX tyres and you'll be fine.
I use the Schwalbe CX comp's and like them very much ... they are light, cheap & versatile :)

+1 on the schwalbe cx compe... it is among the best multi terrain tyres there is.

It may not be exactly "the best" ... but I find it to be the perfect equilibrium between weight, puncture resistance, speed on roads, grip on mud and price.
I bought mine for about 8€, which is well below any other tyre in their range around here.
A few days ago I heard a clicking sound on my back wheel ... it turned out to be a small pointy stake of springy metal that had entered the outer wall of my tyre, hit the puncture resistant layer and was bended back out a few millimeters further.
Back home I could easily remove it from the tyre, which was still in perfect condition, apart from a tiny little hole. :)

that cx comp looks nice. also check out the schwalbe marathon cross for a tire that rolls well on-road but can handle the logging trails you speak of easily.