I’ve gotten my parents a new computer and am setting it up for them before bringing it to them, and I freely concede Vista’s not my strong suit.
I find the OS’s endless “Do you want to run this program?” dialogs that pop up after I personal;ly try to run a program are driving me insane, and if they drive me insane, they’ll make my parents’ heads explode.
Can you stop it from doing this?
Note: Please don’t tell me to buy a Mac. I am looking for technical help.
It’s Vista Home Premium.
Yes. Go into Control Panel and the User Accounts. On the “Make changes to your account” page, select “Turn User Account Control On or Off” and turn off “Use User Account Control (UAC) to help protect your computer”.
Unless your parents are technically savvy, I’d recommend leaving it on once you’re done with it. Leaving it off basically leaves your computer in the more-vulnerable administrative mode, which leaves it much more susceptible to spyware and other viruses without the user’s consent of running them.
Keep yourself as the only admin and do as tanstaafl says. But then make them Limited accounts so they can’t do anything harmful.
I’d recommend leave UAC on too. It seems worse at first, because the first thing one tends to do with a new computer is install a load of stuff on it. But if they’re just using the computer rather than changing anything, perhaps it won’t bother them that much?
I think Microsoft had to walk a fine line between pissing off users and prompting developers to finally make their damn software work under non-admin accounts.
And then be prepared for Vista to bitch about UAC being turned off. 
It’s not very obvious, but in the Security Center, click “Change the way Security Center alerts me” on the left to turn off the nag screen.
Really, once your programs are up and running, you very rarely see that warning anymore. If I see it once a month, I’m startled…but I find it useful. Since your parents probably won’t be adding or changing much, it really won’t be a bother.
Well, …, I see it several times a day for the same programs, over and over. Sometimes Vista just will not remember that you have approved a program. There appear to be a number of things that can trigger this. Running from a network drive, . from an external drive or flashdrive. are the most obvious. (If Vista does not “trust” the drive, it won’t retain your prior decisions about a program.) Then there are a few programs that Vista just seems to dislike and will ask about every time.
As far as giving your parents non-admin logins, just remember that they will be calling you every time they find a new program they want to run. And if an application consists of an entire suite of related executables, you will need to make sure you execute and unblock all of them.