I shoot with the XSi, as does Royden.
You will find the kit lense (18-55mm f3.5/5.6) to work well for most shots.
I shoot with the kit lense alot for regular portraits, If I want to get close up or macro I use my Canon 100mm f2.8 Macro lens. If you are not currently using the manual mode on your camera your really missing out on the full potential of your camera. Shooting in natural sun light will provide the best results, however many of us use flashes when needed. A good flash set up for the XSi is a Canon 580exII or a 430exII with either an omni bounce or a softbox.
-Jay