the original Windowing system Bill Gates took the windows windowing system from. Macs are expensive, but very nice... well if your a none Geek type. Mac's now run on MacOSX, which is based on BSD so now Mac's are Unix based and can run lots of Unix freeware.
I have never owned and hardly ever use a Mac, so i guess some one else should add more to this page
I'm going to have to disagree with the expensive part. Unlike (pre-Vista) Windoze boxes, Macs came with tons of features and therefore required a bit more horsepower than the typical bottom of the line Windoze boxes and therefore were priced higher (so a bottom of the line Mac was (in my opinion) equal to a mid or high level PC and the prices are very similar. Now that Vista is out, the bottom of the line Intel machines will not be able to run Vista and in particular some of the "more Mac like" features (i.e. Aero).
I am a self proclaimed geek and have quite the setup of computers running on my home network. By far, I love my iMac the most. Considering what it is capable of, I would say that the price/feature is well below that of a Vista machine if you were to get all the goodies. You can check out the stats page here or just check out the wiki running on the iMac by visiting the BoswellWiki.
I also love the MacBooks and MacBook Pros. Considering that they are a fully capable desktop grade PC, they are priced well BELOW the prices of similarly equipped laptops from name brand companies.
sid. (184.108.40.206 22:57, 12 February 2007 (CET))