That's good to hear about the salesman. It's getting more rare nowadays to find a good one! I must admit, it's refreshing to hear a salesman actually recommending a look at the Sony - that's very much not been the norm at nearly any photo department in the country, where you tend to only ever hear recommendations of two other brands, regardless of the person's needs, wants, or budget. Sometimes because that's what they know better, sometimes because the cameras they recommend actually are better, and sometimes because they get paid better if a particular brand sells. The other DSLR brands tend to suffer regardless of the reason, even with some pretty nice cameras themselves!
Lenses are important...I'll admit that was a part of my decision to go with the Sony. I liked the fact that all of my lenses would be stabilized, due to the in-body stabilization...both because stabilized lenses are much more pricey, and because there are a number of lenses not even available stabilized from any manufacturer (like some primes). Having an inexpensive backlog of Minolta lenses I can buy used, the current line of Sony lenses, some good third-party stuff, and the high line G and Zeiss options, all helped me feel pretty confident going with the Sony.
The D90 has some serious merit - most notably the high ISO capability - if I was going to do a majority of my shooting in those situations, I'd definitely have moved that camera to the top of my list. Personally, I don't want or need video...so that doesn't move me.
Each camera may have a specific area where they have an advantage - otherwise they're all fairly equal in their abilities and IQ for a majority of normal shooting.
