If you don't know a lot about computers:
Macs are more expensive but have a pretty good operating system for someone who knows nothing about computers.
windows is cheaper but if your not good at computers within a year or so you will have a ton of viruses and your computer will be slow as hell.
linux is free and great but you need someone who knows about computers to set it up.
If you do know a lot about computers:
macs are just overpriced for the hardware they come with. The company is just taking advantage of the sudden apple craze/fad that is occurring due to ipods,ipads and iphones. the os is good though.
Windows is fine as long as you have good antivirus and are a bit careful with what you download. much cheaper than macs 99% of the time.
linux is great just in the past when i used it I had issues with some games and programs. but for general computing like web browsing and word documents and spread sheets there are no issues.
