I found this in an article on the PC World Website. Enjoy~!

Security
Following years of justifiable criticism about Windows security, Microsoft had promised that Vista would be the most secure Windows ever. This goal largely appears to have been met, though at some cost to the user: The OS's nagging User Account Control feature has been roundly lambasted as the Mother of All Windows Annoyances. Other security improvements are less irritating.
XP's version of the Windows Firewall protected you only against inbound threats: If malware infected your PC and attempted an outbound connection, Windows Firewall could do nothing about it.
Vista's firewall includes outbound filtering, though that's not readily apparent by looking at the Windows Firewall Settings tab. To configure outbound connections, you must launch the Windows Firewall with Advanced Security screen by typing wf.msc at a command prompt. We didn't test the firewall's effectiveness in our near-final prerelease copy of Vista, but the presence of outbound filtering could eliminate the need for a third-party firewall for at least some users.
Vista's Security Center is not much different from XP's, with a similar confused interface. Clicking the green button next to the firewall, the automatic updating, and so on does absolutely nothing--just as in XP. But links on the screen's upper left side let you configure security settings.
Windows Defender, Vista's bundled antispyware software, was impressive when PC World tested it under its former name, Windows Anti-Spyware. Its Software Explorer, for example, shows you programs that run at startup and ones currently running, plus details including whether an app is classified as malware. If so, you can take actions such as disabling or removing it. Like other antispyware apps, it provides real-time protection and performs daily system scans at a time you choose.
New, less visible features include Network Access Protection, which lets network administrators set requirements a PC must meet to connect to the network (current antivirus signatures, for example). BitLocker Drive Encryption, available only in Vista Enterprise and Ultimate, enables hardware-based lockdowns of a PC and its data.
Because so many attacks on Windows exploited security holes in Internet Explorer, Microsoft has beefed up Internet Explorer 7's defenses. Like other IE 7 features in Vista, most of these security improvements--including phishing site filters and address bars in pop-ups--duplicate those in the Windows XP version of the updated browser (see our review, "Radically New IE 7 or Updated Mozilla Firefox 2--Which Browser Is Better?"). One big difference: In Vista, IE 7 runs by default in the new Protected Mode, which keeps it from changing system files or settings.
(Seletion from
http://www.pcworld.com/printable/article/id,127629/printable.html, the article is called "Everything You Need to Know About Windows Vista", and it is by Preston Gralla... Obviously not me.

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