With Microsoft's new Windows 7 operating system (OS), available in Home Premium, Professional and Ultimate flavors, most of the improvements over previous iterations are under the hood. But while boasting increased performance, stability and better memory management, Windows 7 is also the most visually elegant, easily customizable and user-centric version of Windows yet.

A Jump Lists feature, for example, gives two-click access to recently used applications and files. There’s also a new Taskbar that organizes applications, much like the dock on Apple's Mac OS X.

Windows 7 also comes with Internet Explorer 8, a faster and more compliant version of Microsoft’s web browser.

Interestingly, there’s less "bloatware" out of the box, which means you don’t have to worry about programs and services you will never use taking up valuable space and resources.

You are given the option of installing Windows Live Essentials, a one-stop download for supplemental apps like Mail, Photo, Blogging, Messenger, Movie Maker and more, but Microsoft has made the gracious effort to not force these apps down your throat.

And where the three-year-old pariah that was Windows Vista required new and fairly robust hardware if you wanted to run it, Windows 7 shares the same system requirements. Moore's law being what it is, a two- or three-year-old (or newer) PC should be up to snuff with the system requirements of Windows 7, with few or no hardware upgrades needed (certain PC peripherals, on the other hand, may not be up for the task).

To be sure, Microsoft offers a downloadable "Windows 7 Upgrade Advisor" tool on the Windows 7 web site that will suss out the specs on your current PC to see it's fit to run the new OS.

As an upgrade for Vista, a lot of the muscle of Windows 7 has already been flexing in PCs running the most recent version of Windows Vista, i.e. Service Pack 2. In fact, 2009’s Windows Vista is a different beast from the half-baked and buggy Vista of 2006, thanks to numerous patches and updates that Service Packs are wont to provide.

That being said, moving up from Vista to Windows 7 yields an incremental increase in overall performance, better battery power management for notebooks and also improved Internet connectivity. Nothing earth-shaking, just more shine, polish and snappiness all around; nice to have but not a critical upgrade.

Anyway, upgrading from Vista Home Basic to Windows 7 Home Premium took roughly 2 hours on a Sony netbook with a modest 1.33GHz Atom Processor and 2GB of RAM. Most of the drivers worked fine, and those that were outdated were replaced by Windows 7, which is also a background process that keeps everything up to date.

Previously, the performance of Vista on this netbook was sluggish and labored, but with Windows 7 there is noticeably less hanging and better performance - especially when playing back full screen YouTube videos, which Vista couldn’t do on this netbook.

The biggest difference is seen in the startup, shutdown and wake-from-sleep operations, which are notably faster.

Upgrading from Windows XP to Windows 7 is an entirely different animal. There is no direct upgrade path from Windows XP to Windows 7, which means you'll need to backup your files and applications and do a "clean install" of Windows 7, which includes wiping your hard drive and erasing everything previously on it. Alternately, you could do the "clean install" on a separate empty hard drive, new ones being cheap-like-borscht these days. Nevertheless, you'll still need to reinstall all your preferred XP applications - with no guarantee that any of them will gel well with the new OS. For some, this will be painful and time consuming.

A clean install of Windows 7 Ultimate on a recent 2.16GHz Quad Core AMD Phenom desktop with 4GB of memory took all of 35 minutes. What took much longer was installing old applications, downloading patches and transferring in a bunch of backed up files.

Horrifically, the Wi-Fi adaptor on this test rig was not recognized and none of the available Vista drivers for the device were compatible with Windows 7. So much for backward peripherals.

Now, two days after the installation, upon waking from hibernation, up popped the blue screen of death - a good old, time-honored Windows crash. What caused it remains a mystery and it hasn't happened since, but there it is.

Windows 7's selective incompatibility and lack of certain device drivers (especially for the 64-Bit version) is an issue that will probably be resolved in time, but owners of non-branded PCs with no tech-support will need to take extra care to ensure that all their devices and programs are compatible and working with Windows 7, or just wait a while.

Likewise, users with older machines happily running Windows XP might want to hold off taking the upgrade plunge, or might rather consider buying a brand new PC preloaded with Windows 7 and be done with it.

Ironically, the inability to do a straight upgrade from Windows XP to Windows 7 isn't going to help Microsoft earn any fans. After all, Vista was so widely lamented that many users opted to stick with or even revert back to Windows XP until something better came along - which Windows 7 certainly is. But punishing those who stuck with the more stable XP seems rude. Or a good reason to buy a Mac, maybe.

That said, jumping from Windows Vista to Windows 7 makes way more sense. It's cheaper and easier and a natural evolutionary step up.