If you cannot get rid of it in windows, you may have an issue removing it unless your in safe mode.
I'd get the following two:
Spybot: Search and Destroy - Spyware Removal
Avira AntiVir Personal - Virus Removal
I've used S&D for years now, it's a great program, not only does it remove, it has another two great features:
A. Immunize - This protects your browsers from several spyware issues, thus you have to worry less because we all know how parents are on computers. Basicly, to date now, it protects 123000+ spywares, thus lessening the chance of even getting it in the first place.
B. TeaTimer - This stays on real time, and protects the computer real time. If something tries to get in your registry, it will ask if you wish to allow or disallow. For your parents, if they don't know much, set it to AUTODISALLOW, and they shouldn't see spyware ever again. Else, just tell them to DISALLOW unless there installing something. Mine hardly comes up now though, unless something harsh happens, it has a smart thing now that blocks garbage automatically, and hardly takes up memory.
And for Avira, I just switched to it about a year ago, and I'm quite happy with it. Norton is BLOATED, takes up huge amount of ram, and takes a hour to load even the GUI screen. It's a good scanner in general, but it has issues with alot of installed programs that are 'fine'. I recently had AVG FREE, but they went to the super BLOATED mode. The problem with those two are it takes ages to load at windows startup, well, too long for me anyways. Don't need a bloated scanner.
With Avira, it has several options, and is a light scanner. Protects real time, emails, etc. Doesn't take up much memory at all either.
To remove anything that cannot be removed by normal scan means, first, get both programs, update them, immunize, etc.. Then go into safe mode (Tap the F8 key at bootup), and after it loads, run the scanners in safe mode. Safe mode basicly means that no programs load, so any program that keeps staying in memory even if you taskmanager close it (ALTCTRLDEL the sucker) it should kill it. Sometimes when you do scans and it removes, the virus/spyware comes back because its sitting in the core of the memory, laughing at you, basicly.
After you do safe mode tricks, you shouldn't really need to do it again. Been going strong now without having to scan -- ever.. Bout a year and half now with no scanning, just using the real time protection.
And a note: If they still have IE6, it is a big security risk, get opera or FF (or IE7). If they know how to use IE6 it would be fine, but like my parents, they click install on everything that pops up.. :x If you hate tabs in IE7 etc, you can always disable them so it acts like IE6.
P.S. If that still does not work, get HIJACK THIS!, and post a log up. You'll want to clean hijack this in safe mode too
Malwarebytes Anti Malware
Is a free program also. It detects malwares that S&D and a Virus protector will not be able to find or localize. It even scans your registry and deletes any files that is infected. It made my laptop seem like I just took it out of the UPS Box when I bought it directly from Toshiba. XD