I read through the previous answers...
Apple today is not the Apple of a couple of years ago. The major change was that they switched to Intel processors. This was a major course change and put them on the main line of the computing world. There are several applications that allow you to run XP or Vista as well as OSX on a Mac.
I will get a new iMac when I can afford it. So you know where I am coming from.
There is the Apple method, which allows you to boot into either Windows or OSX. But you have to reboot to start either one. At first this seems like a poor choice until you realize that for the smaller systems with smaller disks and memory capacity, trying to run both systems at one time is just a bit too much. Running them one at a time is fine.
If you get additional memory and hard drive capacity you can get applications that allow you to run both Windows and OSX together and move more or less seamlessly - even using copy/paste - between them. It depends on which application you use as the link between them.
I saw that one of the systems puts the Windows OS behind OSX which means that the Windows vulnerabilities and open ports can not be scanned by a hacker. That sounded good to me...
I have to comment on the out dated opinions I saw in your answers. They are old hat! They should take a look at the new specs. If you want a top end computer, the new Mac Pro is running at 3.2 GHz and has 8 cores. It is not like actually having an 8 CPU computer, but it is almost twice as fast the previous Mac Pro that had 4 cores.
But a business doesn't need that. What you need is the back up system they call 'Time Machine.' If you have a business with lots of huge files such as high definition images, videos, or sound files, get a huge external hard drive. Memory capacities are going nowhere but up. Pretty soon it will take several double layer DVDs to back up all the files people will collect. But is you are just using it for your business, well, only you know about how much backing up you will need.... Figure it out and then double your estimate! The top end Macs come with 4 Terabytes of internal storage. 4,000 gigabytes!
As far as the learning curve regarding the change goes, you have to find out if your business application will be the same as you use now or if you will change to something else.
One way to make the transition simple is to buy a used Mac to play with at home first. If you want to work at home at times and take your work files home with you, then you need a more modern Mac that will run OSX 10.5. If you just want to get used to using a Mac, then you can find very cheap Macs out there. OSX 10.5 is a major upgrade and you should get a machine that will run it. I have two Mac that I use regularly. One is a 2001 eMac and the other is a 2002 eMac. This machine was replaced with the iMac. Now as applications migrate over to the new OS, I can not run the latest versions. That is the main reason I will eventually get a new iMac. The eMacs have reached end of life and soon will not be repaired by Apple. But I am going to run them into the ground until they are really dead. I have replaced both DVD drives and had to repair a fan. Other than that I have had no trouble other than their growing obsolescence. I have never been a first adopter. Obviously! But the iMac is one of the best consumer computers ever made. That is the judgement of the PC magazines I have read. Google 'iMac Review' if you want to read them yourself.
I also use Windows XP and 2000 4 days a week. At least I did until I was forced to scrap 2000 as too cranky to llive with! I have had 1 major crash and 1 minor crash and about 50 virus and trojan infections since September which I get via the USB disk that I carry around to all the PC's I must work on. Every day I would go home and kill the infections on the USB using AVG. I would back up daily. During that time, I had no infections on the eMacs even though I used the same USB disk with them.
The biggest problem was the invisible files that OSX places on the USB that were not invisible on the PC. The clutter was annoying. The files are harmless to a PC. They just help OSX remember stuff like which thumbnail size was being used or where on the screen a file was being kept. Windows doesn't care about those files. But if you copy files over to a USB from a Mac, the Mac will copy those files automatically. If the USB is a music player, these files will confuse the player and it will try to play them and give an error message. There are copy apps that will copy only the useful files though.
;-D Once you get used to using a Mac, you will have little patience with how the PC does the same thing. I use Word, Excel, PowerPoint, QuickTime, iTunes, Opera and Firefox on both platforms. The biggest problem I have on the Mac is that using Chinese characters in Microsoft apps are sometimes not displayed properly. They display properly in all the other apps. This could be my problem since I don't know how to tell the apps to use the chinese fonts. You are going to love a new iMac and a new laptop if you get a MacBook. My daughter uses the iMac 20" and my son uses a 17 inch PowerBook. My wife uses a 12 inch PowerBook. They are all happy with them. Enjoy!