With regards to expense when comparing a pc or a macbook, you get what you pay for. The initial cost is more for the macbook but you'll have a happier experience because of it.
Take iLife for example, comes already installed. iMovie is a huge leap up from windows movie maker, it's kind of in between Movie Maker and say Sony Vegas. iPhoto is a superb piece of software for viewing and organising images, much better than anything you get free on windows.
Then there is antivirus software, you'll need to get some for a windows machine so you can either purchase norton or go with one of the free ones like avast with less protection. Essentially it's a pain, it can be a draw on your cpu, it can pick up trojon viruses in programs when they aren't there, it'll make using your machine more irritating because of all the alerts and scans that need to go on and if you do get norton it will eventually double the time it takes to boot up. Mac is based on UNIX and as such it is more difficult to write viruses for, also with it being the minority system there aren't as many viruses around for it because the virus maker wants to infect the biggest audience. You won't need virus protection for your mac. Your mac can still get a virus, but the chances are a lot slimmer, I don't know a single person who has virus software for their mac and when I did run a scan on my 4 year old macbook that had never had a single piece of virus software on it it came up clean.
Then there is drivers, anything you plug into the pc will need a driver installed. I've yet to have to install a single driver for anything I have plugged into my mac. Sometimes drivers fail and you have to go into device manager in widnows, uninstall, re-install - pain in the butt.
Then there is maintenance. Someone on here said windows will get slow and bogged down if you don't clean it up avery once in a while. With a mac you'll just not need to do that, so whilst a windows user may see this routine maintenance as just part of the process, to a mac user it's just another pain in the ass.
So thats why it's worth paying more money in my opinion, it's like flying. You can pay ryanair fees and get to spain but the service will suck, or you could fly British Airways and get a meal, a movie and more legroom. Both flights will get you to SPain but the journey will be very different. The BA will cost more but will be more enjoyable