[citation][nom]w3k3m[/nom]I'm running XP and I still see no need to upgrade to Windows 7 (and I tested it for a longer time). For the most part, I see Windows 7 as Vista with some junk removed (which you can do manually as well).For me it got be some major architectural change to justify the upgrade(like it was with Win 9x -> XP). Tons of useless gimmicks don't make my work routine any faster, actually it just distracts me. As for stability Windows 7 is no match for tried and tested Windows XP.[/citation]
a lot of the advantage to Windows 7 and Vista aren't something you can see. The security mentality is totally different with the newer OSes.
There are 3 main advantages that make Windows 7 and Window Vista better from a security standpoint: UAC, Memory randomization, and Network security.
UAC keeps the smarter users from getting hit with viruses and spyware. there isn't a way to get past it if it is combined with removing the user's admin rights. Some people find this annoying, but those are the stupid people who get infected with malware all the time anyway. If you recognize the usefulness (and the fact that both Apple's OSX and Linux use this same format, only requiring passwords as well) then you learn to live with it just to keep your box safe. (Of course, I can't run WoW without admin right either, so I have to keep my admin rights on my main user account. It's annoying, but when the program needs to be patched, then it needs to be patched.)
Memory randomization reduces the ability of malware to run its code using buffer overflows. I'm not certain how this is accomplished, since I'm not a programmer, but that was the biggest obstacle for the guy who hacked IE8 in the last hacker contest. I guess it took him an extra week to get around that part of Windows 7 security. Many of the troublemaker hackers are too lazy to bother with trying to get past that. The profit seeking ones will get past it, however. That's where UAC comes in to help protect.
The network security is far, far superior to XP, though. XP's firewall is a "allow unless blocked" type setup while Vista and 7 have a "deny unless allowed" setup. This means that all ports are blocked from the outside unless you specifically open them, unlike XP, which leaves all the ports open to outside access unless specifically blocked.
There is also a non-security related improvement that I can really appreciate: not needing a floppy drive for SCSI and RAID controller drivers during installation. Considering how many times I've had to reinstall XP and needed a stupid floppy drive to get a driver, I'm really happy about that part.
There are also some other differences that are of limited value, such as DirectX 10 and 11 that allows more direct access to hardware. However, those aren't really worth mentioning.