The XSi (or any dSLR) should easily do the job, but you will need to have the right lens. In honesty I would be looking for wider than has been suggested. Something like the Sigma 10-20mm or the Canon 10-22mm would fit the bill for what you need.
As for the lighting, this will be the same with any camera, you need to learn how to control the settings to get better results than just what it will give you. The main thing will be to control exposure if you have a window you want to show off or see the lighting from etc.
For learning how to better set your camera Steve's is a good place to learn.
Hope that helps.
Edit, as every when writinga post at the same time as John you know you will look lazy and uneducated LOL.