I added an iMac 27 to my computer system 2 years ago, after having yet another hang up with Win 7 Pro. I bought it primarily to have a reliable workhorse with which to do email, some documents and spreadsheets, and picture cataloging and storage. It sits alongside the home brew PC that has lots of memory, storage, and speed, and runs Win 7 Pro x64.
Both machines have as much memory as I can afford...the iMac has 8 gb while the PC has 16 gb. The iMac has an Intel 7 x 4 core cpu while the PC has an AMD x 6 cpu. The PC came with NO software (my wife's HP laptop came with lots of crap ware), while the iMac came with with a full office suite with iTunes and iPhoto included.
After two years, here's what I have concluded: the iMac is far more reliable than the PC. Did I mention that one can only run Apple-approved software downloaded from the App Store to keep the iMac reliable? Did I mention that the iMac came with a reasonably powerful suite of office apps to do all that I needed. Don't be fooled: the iMac sometimes does hangup, but a reboot and reset generally takes care of it. It has lately developed a problem in which core temps (easily measured on the iMac) got excessively high, and I had to take the machine to a certified repair center where they found nothing wrong. But installing two apps to measure temps and set the fan controls manually solved the problem.
OTOH, I still need the PC. The flight simulators for models won't run on the mac well (yes, I know about VMWare and others), and some programs are just not well ported to the mac (one family tree program, one financial program).
If you buy an Apple laptop, you will have to accept that you cannot run certain programs unless the machine has a powerful processor and plenty of memory to allow windows to run as a VM. Yet the Apple software is more than adequate to meet most every 'office' need, and it is reliable.
If you learn to use some great open software such as Open Office and Thunderbird, your Mac experience will be enhanced.
As for me, I would get a well-outfitted Win 7 Pro laptop, and an iMac desktop. Seems to me, this is the best combo. If you can only get one, you will have to choose.