I was comparing the two versions  Leopard and the newly arrived Snow Leopard…. decided to upgrade this week or so, gotta take a walk to our small Apple shop. Here are some reasons to upgrade:

10. It’s Leopard Done Right
The release of Mac OS X Leopard was fraught with peril. It was late, it ran a bit slow, and it offered amazing new features — some of which weren’t fully ready for prime time. Snow Leopard is all about performance, optimizing features to deliver a great experience. It takes what you know today and makes it perfect.

9. It’s only $30
Recognizing that it has an evolution, not a revolution, on its hands, Apple’s keeping Snow Leopard incredibly cheap for existing Leopard users. At $30, it’s more than we paid to move from 10.0 to 10.1 (which was free), but it’s still one heck of a bargain. And it’s only $50 for a family pack.

8. You’ll add six gigs to your hard drive
This is a no-brainer. If you install Snow Leopard, your hard drive gets bigger — it takes up six or seven fewer gigabytes than Leopard. It’s less bloated in more ways than one.

7. Smarter Stacks and Expose
The OS X Finder already contains some of the most innovative UI elements ever. Snow Leopard makes them smarter. Stacks allows scrolling and advanced support for multiple folders now. And Expose allows you to just click on an app’s icon, thereby allowing you to select between that app’s windows.

6. It’s fully 64-bit, so buy 17.2 billion gigs of RAM!
If you own a recent Mac (anything with a Core 2 Duo), you’ve got a 64-bit processor. And with a fully rewritten Finder and under-the-hood code, Snow Leopard will let you manipulate absolutely gigantic files, up to 17.2 billion gigabytes at a time. Basically, if you’re doing high-end photo or video work, this will be the best platform ever.

5. Killer Multiprocessing with Grand Central
Apple’s been pushing multiprocessing since at least 2000, but the promise has never really paid off for most users. Snow Leopard aims to change that with Grand Central Dispatch, a powerful API for creating multicore-optimized code. Some apps will run faster right away, and it will only get better over time as other developers get caught up. It will be the gift that keeps on giving.

4. Unleash the Power of Your GPU With OpenCL
Time was, Windows lovers could (justifiably) deride the 3-D graphics power being packed by Macs. Anyone who tried to run Quake III Arena on a first-gen iMac can remember the pain we all shared. That’s changed now. The integrated NVIDIA graphics in even Apple’s low-end machines are totally respectable, and the dedicated cards in the MacBook Pro and Mac Pro are downright brawny. Unfortunately, unless you’re a gamer, an architect or an industrial designer, that probably doesn’t matter much to you. That’s why OpenCL is so great — it’s a coding framework that allows ordinary applications to tap into the extra power in your graphics card for all tasks, from web browsing to iPhoto. Snow Leopard’s all about power, and OpenCL’s a big part of it.

3. Native Exchange Support
A lot of factors have kept Macs out of the office over the years, but none has been more significant than the lack of MS Exchange e-mail, address book and calendar support. Outlook is as close to a standard as a proprietary format ever comes, and Apple’s taking its experiments with Exchange on the iPhone to the desktop. From now on, anyone with a Mac can make appointments, view contacts, and send e-mail via Exchange. I don’t know if I’ll ever bring my work computer home again.

2. QuickTime X Restores What the Tech Was Meant to Be
One of the great disappointments of long-time Mac users has been watching the slow decline of QuickTime. Once a legendary consumer multimedia player and editor, it increasingly became over-shadowed by iLife and iMovie. Charging for the Pro version meant that most people steered clear of it entirely (I couldn’t tell you the last time I played a video in QuickTime Player). QuickTime X fixes all of that. A ground-up rewrite, X integrates all former Pro versions into a free version for the rest of us. It’s two-and-a-half times faster than previous versions, plus built-in authoring capabilities, including recording via iSight and microphone, YouTube and Mobile Me uploads, and export to iPhone. Basically, it’s finally Apple giving some love to the multimedia technology that started it all.

1. Because You, Like Me, Are a Gigantic Apple Fanboy or -girl
It’s OK. We have a cult for that. Think it’ll make it here by Saturday?

Some text copied from http://www.cultofmac.com/10-reasons-why-snow-leopard-is-an-essential-upgrade/15010