would be more than enough to cover what your wife plans to do.
Default browser in OS X is Safari, with Firefox/Chrome/others, being alternatives.
Fortunately there is no Internet Explorer for Mac. You should not have any difficulty with accessing websites with the available browsers.
The default mail program is Mail and it has no problem receiving mail from the "rest of the world"
iWork does have similar functionality to Office and is also able to open/save documents in MS Office format.
Open Office has problems with formatting.
If you really want to stick with MS Office, there is a version for the Mac. It plays quite nicely with the Windows version.
Time Machine would be your backup strategy of choice, it just involves attaching a Hard Drive to the Mac and turning on Time Machine.
Backups are automatic and very reliable.
Of course there will be a learning curve during the transition but as long as you approach everything with an open mind, you will find that there is nothing that you used to do on the the Dell that you cannot do on the Mac.
Let us know how you get on
P
My wife's old Dell laptop is on its last legs, and we are considering a Macbook Pro as a replacement. However, since neither of us knows much about Macs we are a bit unsure what she needs. I haven't used a Mac since about 1991 so there have been a few changes!
My wife mostly uses the computer for web access, email, photo storage and genealogy research. We have verified that the genealogy program she uses has a Mac version that can interact with the Windows version she currently uses. She does a little word processing and has rarely used PowerPoint or Excel.
I know that there are various browser options. I assume Safari is the default browser. I hope IE is still an option since so many sites are flaky with non-IE browsers.
I don't know what the options are for email and how well the default email works with email from the rest of the world (eg: Outlook).
The Apple store offers iWork, which appears to have similar functionality to MS Office, and it also offers a couple of versions of Office. How well do these products interact with the Windows versions? I know that compatibility is difficult. Some of the documents I use look different in Open Office than they do in MS Office. How common is that kind of problem with the Mac products?
Any thoughts about problems we are likely to encounter during the transition?
One problem I know about is that our home network backup system (Windows Home Server) does not generally play nice with Time Machine and I am not sure how to approach that.
Any suggestions/thoughts for this Mac newbie will be appreciated.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic