OSX
7 million users...transition is almost finished. So if your in 9 still, get with the program. Even Jaguar is "over."

Over 100 new features:

• Most popular Unix in the world
• Lots of techie ??? stuff that I dont understand
• Brand new finder...user-centric. All the folders you want in the top level of your file directory.
• Fast searching and labels!
• Dynamic network browser
• Improvements in iDisk - Automatic sync of files of local folders in the background
• Exposé? Solve the clutter problem...holy crap! Gives you a thumbnail view of all your open windows! It can be application specific is you want. Triggered by keyboard, 2 button mouse or a hot corner. I think I will be changing the option key modifier on my mouse soon. Quartz Extreme based.
• FileVault: file security for notebooks. Secures your Home folder by encrypting/decrypting on the fly.
• Mail is "faster"...Safari rendering...addresses are objects so they're easier to manage in your emails
• Industry-standard VPN
• Built in fax - Every print panel has a fax button
• Pixlet: studio grade codec for film quality (HD) material with no noticeable compression artifacts.
• Preview...will be the fastest PDF reader in the world. Good thing too because it sucks now. 3x faster than the Windows version. Includes search. Create PDFs from any app with on-the-fly PostScript conversion.
• Fast user switching - change users with menu in top right corner...slick!
• FontBook...pro font management. Lists all fonts at any size with font preview
•Best for last...iChat is now iChat AV. Adds audio and video chats. Video conferencing for the rest of us with zero configurations. Works with any FireWire camera including camcorders. Broadband required for video.