Security
When it comes to security, Microsoft has a rather patchy' reputation, if you'll excuse the pun. The improved UAC slider control in Windows 7 means that users will be less likely to feel like they have to turn it off, which should, in theory anyway, add a layer protection that might otherwise not have been there.
Windows Vista got brownie points for introducing BitLocker which added file level encryption to the operating system itself, which was a good move. Windows 7 took it a step further with BitLocker to Go bringing it to portable devices such as USB flash drives.
The Firewall in Windows 7 is also more flexible. You can use network profiles to offer different levels of blocking for incoming connections depending on whether you're at home, at work, or in public.
Most of the major work under the hood in terms of security was done in Windows Vista so it deserves recognition for that. It's just the over the hood visual stuff that made it all easier to use in Windows 7.
Neither has any built in anti-virus but after you install Window 7, it makes it easy to find a compatible free suite from a variety of vendors, while Microsoft itself has done a better job with its Security Essentials than it did with its Vista era OneCare suite.
Winner: Windows 7
Performance
Windows Vista's performance troubles have been well documented. The operating system required much more hardware than XP did and if you performed a straight upgrade without new hardware you were asking for trouble. 1GB of RAM became the new realistic minimum, but really you needed 2GB of RAM to stop Vista from being a pain in the proverbial.
Once the system was clogged start up and shut down times dropped behind that of XP and moving around Vista compared to XP always felt sluggish. The worst aspect though was file copying on Vista. On its initial release, many users complained of very poor performance when copying files from one location to another. For a basic function of the operating system this was a serious issue. It was particularly bad over networks which, as home and office networks developed, was far from ideal. Many downgraded or shunned Vista for this very reason.
Microsoft eventually addressed the file copying issue in Service Pack one, but for many the damage had already been done.
Windows 7 fortunately does not suffer from any bizarre basic quirks such as this and also benefits from the fact that hardware has become more powerful and more affordable since Vista was released. What Microsoft has to take credit for is making Windows 7 even lighter on its feet that Windows Vista, which is the first time Microsoft has ever managed to achieve this with a new operating system.
Upgrading from Vista to Windows 7 with no hardware changes will provide the same or possibly better experience, particularly if you perform a clean install. It's even comfortable on low-power netbooks.
Windows 7 also enjoys better startup and shutdown times thanks to minor low-level tweaking, and though it's only a minor improvement this sort of enhanced responsiveness is always welcome.
More intelligent power management also means you can eke out more battery life from your laptop or netbook - another great productivity boon.
Winner: Windows 7
