iLivid and associated infections

My child tried to download something and ended up downloading iLivid and several other malware items as well at the same time. Needless to say, Norton and Microsoft's Security Essentials have been useless, not even detecting them. I've been reading posts here and elsewhere, and not only is it malicious but it changes frequently, which might explain why some of the names differ from previous posts. Over a number of hours now, I've tried several things to remove them. I succeeded in disabling and hopefully removing the browser hijack (Default Search?), but there seems to be a few lingering remnants, based on an OTL scan (e.g., MusicOasis, Tarma Installer, Yahoo! Companion) that were installed at the same time. I am concerned about what evil any remaining pieces are capable of perpetrating. [The only bright side so far is that this has been a useful teaching moment for my child.] Really need help and am very grateful!