I own a 17-inch Powerbook and use it as my main computer. I am very happy with it (but as a caveat, have owned Apples since 1984).
What software does your wife need to run? The Mac comes with a suite of basic apps, such as ITunes, browser, a good e-mailer, etc. There are Mac versions of most mainstream software such as Microsoft Office, Adobe products (Photoshop, Acrobat, etc.), and the like.
If she has PC programs that aren't available for the Mac, VirtualPC by Microsoft permits you to run most PC programs. It's suitable for office software and the like, but I wouldn't try to run high-end games on it.
I wouldn't hardsell you on Mac, but by all means drop by the Apple store and ask one of the staff to show you the ropes. Their service support is rated as outstanding, which is in time can be as important as the computer.
She'll run Office mostly. I can get the MS version for the Apple. Does Apple have a good mail program or does MS make Outlook for Apple?