The Windows experience on a Mac is exactly the same as on a PC. If you look at the hardware of a Mac, you will see that it has got hardware of a PC, but instead of running Windows by default, it comes with OS X. Windows works without any problem on a Mac, and new Macs now only support 64-bit Windows 7 and Windows 8
The experience is not "exactly" the same as there are a couple quirks, but it's close enough.
When people are looking at Macs, if they plan to use Windows as well, my general rule of thumb is that unless you're going to be working in OS X at least 70-75% of the time you're on the computer, just buy a Windows machine from the get go. It doesn't make much sense to pay the "Apple tax" on the hardware plus the cost of a new Windows license if you're going to be using Windows most of the time.
I was a "hardcore Windows guy" when I bought my first Mac in late 2007. I purchased a bundle deal that included Parallels and Windows XP along with the 17" MacBook Pro I purchased. At first, I would run Windows about 75% of the time, and spend the rest of my time in Boot Camp (for performance reasons). As time progressed, I started spending less time in Windows (I started getting used to my Mac OS and the way things are done diferentely.
Before I owned my Mac, I would upgrade my Windows Laptops (Dell or IBM ThinkPad) about every 2 years. When I bought my first MacBook Pro, in Late 2007, I used it up until early 2012, when I replaced it with a new MacBook Pro. I've been using my "new" MacBook Pro for about a year now, and I don't have Boot Camp loaded. I only have Windows loaded in a virtual machine using Parallels. I also only run Windows about 5-10% of the time now because I have found Mac OS apps (or Mac versions of my favorite Windows Apps).
I'm not saying that your friend will be like me, but there is a chance. With the current Mac hardware, running a virtual Windows machine is so easy. I have Win 7 32 bit running in a virtual machine, wher eI have given it access to 4GB RAM and 100GB drive space, and my current Mac OS doesn't even notice when it's running. The Windows side runs just as fast as the native Windows running on my Core2 Duo ThinkPad that I keep around as a spare for my wife. For my needs, 32 bit WIndows is all I need, and it is so easy to run that in a virtual environment, so that is what I do.
Sounds like Parallels and a virtual Windows setup is the best way to go. I don't think my friend is gonna be running sophisticated software, but he is a realtor and I know from experience that some of the programs realtors use to do business do not run well on Macs, even though they are web-based for the most part.
Thanks you everyone for your comments. I feel more comfortable recommending he switch to a Mac knowing that his Windows requirements will be met with a minimum of bother.