Unless the salesperson is matching your knowledge base to a simple camera, I just don't understand the recommendation. The XTi is in a whole different league. I have a stock answer about SLR's vs. Point & Shoots, so here you go:

SLR vs. P&S

"Single Lens Reflex" means that the camera has only one lens (which is true for almost all cameras these days anyhow) and the light follows a "reflex" or reflected path through the lens, through the camera and up to the viewfinder where you look when you compose your shot. Many years ago, there used to be a separate lens for the viewfinder and another one for exposing the film. These were called "Twin Lens Reflex" cameras. Hence the distinction of "SLR" came into being.

Today, an SLR still uses one lens for taking the picture, but the most important distinction is that the lens can be removed from the camera so that you can interchange lenses for different shooting situations, if you desire. For most casual photographers, one general purpose zoom lens will suffice most of the time, but you have the option of buying new lenses to give your camera different capabilities as your interests change.

A point-and-shoot (P&S) camera is set up so that you don't need to know much more than how to aim the camera (the "point" part) and press the button (the "shoot" part). While you can use pretty much any SLR in the same manner, this is almost the limit with many P&S cameras. The user can exercise a little control if desired, but it's usually easier just to stick to the automatic mode for 80-90% of your shots. P&S cameras do not have interchangeable lenses.

P&S cameras are generally a lot smaller than SLR's and many of them are small enough to fit into a shirt pocket with ease.

To ME, the major distinction between the two styles is the image quality. P&S cameras have much smaller sensors, which is where the camera captures the light to make the image. The larger the sensor, as a rule, the better the image quality. For a typical 4" x 6" print of the entire shot, this doesn't make a whole lot of difference, but if you want to make an enlargement of a portion of your picture, the SLR with its larger sensor will give a much better result. Most P&S cameras have a sensor that is only about 4 mm x 5 mm. A few have the larger 7 mm x 5 mm size. Most SLR sensors range from 14.8 mm x 22.2 mm to 15.5 mm x 23.6 mm. (There are some smaller and some larger, though.) This is about 10-to-20 times bigger than a P&S sensor.

Go here http://www.flickr.com/photos/samfeinstein/476181751/ and click on "All sizes" and then "Original" to see the difference. Read the text for more explanation.

Do the same for this pair of shots:
http://www.flickr.com/photos/samfeinstein/1098666030/
http://www.flickr.com/photos/samfeinstein/1198936061/

The first one is taken with a Canon Powershot SD900, which is a pretty darn good camera by P&S standards. The second one is taken with a Nikon D200, also a prety darn good camera by SLR standards, but it could have been done with almost any other SLR out there with similar results.