Viruses/malware/spyware are always going to exist, no matter what. You think this is going to stop the script kiddies?
It can and does hinder them a great deal, yes.
The Malware and Spyware and alot of viruses that exist today won't run or infiltrate a system that is used by a standard user that uses elevated privileges only when needed. With or without Anti-whatever. It's just a simple fact, they won't have access to parts of the system they require.
XP was loved by sysadmins, Vista was shunned by corporations and governments.
XP was heavily shunned in the beginning by these very same groups in favor of Win 2000 and NT4 by some.
The biggest problem with Vista was change again. Most software that would not run with UAC was due to coding by those dev's. Large majority of software works just fine.
2nd, UAC shocked and scared a lot of people, they are starting to understand it more and be more accepting.
3rd, none of the big OEM manufactureres of hardware/software, PC Dealers (Dell, HP, Sony, etc.) were not ready (or they just didn't want to prepare for it as they assumed Vista would be as bad as ME, which it is not). They didn't prepare, they had ample time to be ready, as much time, if not more than with Win7. These groups can take the largest ammount of blame. With number 4
4th, the most aggregis of all of them,,, The Big OEM's (Dell, HP, Sony, etc.) sold crap systems with 512M of ram and low end celerons with Vista on them, knowing full well it was going to be shit. But, people wanted to save money and have the latest OS. These OEM's should have told them no, we can't sell you a system with those specs and vista, you can get it with XP. At the time, you could order either.
I also sold PC's for a while and would never sell anyone a PC with those specs.
Sure, Vista will run, till you install your first app (usually Norton 360 or Mcafee {crap} from those OEM's) then puke. Then people would blame Vista.
Alot of so called Vista problems were not caused by Vista being Vista.
It's shotty hardware and not ready software/drivers etc. and end users.
I have yet to have Vista BSOD, Lockup, Crash, cause problems that I did not do myself, knowing I was about to make something bad happen.
Infact, I have an aunt and uncle, that I sold a vista system to, I still talk to them, and insist they call me if they have problems. I don't hear from them, they surf the internet and use email mostly, but they don't have problems. And when I ask, everything is running fine. They know nothing about PC's, OS's or anything, if they can use Vista with UAC and not complain or have issues? hmmm.