Well, if the advertising and press can be believed, it's appears to be a good solution if what you're wanting to do is monitor activities from a remote computer, keep logs of chat sessions for later viewing, etc. If they'll actually take the time to do that and make it clear that they are looking at what she does, it might work as a preventative tool, but it sounds to me like they're more interested in a hands-off approach. This software is really intended for use by network administrators in an environment that makes physically watching users all the time impossible. Like you I believe, I don't see the point in spending money on something that could be done by moving the physical machine to a common room. The latter would accomplish the same purpose, probably more efficiently and certainly less expensively.
What, exactly, are they trying to accomplish, restrict access during certain times, restrict websites, chat networks altogether, or what? There are different ways to go about each problem, but the important thing to remember is that any software based solution can be beaten if the kid knows what he or she is doing. Again, physical access is root access. Put in all the best software imaginable, fail to password protect the BIOS, and you can get around it with a simple Live disc.
I hate to put it this way, but if what they are wanting to do is keep her out of chat rooms, it's going to take a low-tech solution to really address the problem, i.e. old-fashioned parenting and teaching your kids it is an incredibly stupid thing to randomly flirt with faceless strangers, and at the end of the day, you just have to hope you've taught the right lessons. You can get in a chat room just about anywhere. We've got display computers at work set up with MSN Messenger, and random people off the street come in and will stand there until they're tired of us asking to help them, chatting with random people elsewhere. It's like drinking or sex. They may not be doing it at home, but that's not going to keep them from it elsewhere.
As for the home solution, if they refuse to put the computer in a common room, they're going to need to start from scratch and set up the computer with a carefully considered security policy. First, they need to password protect the BIOS to prevent anyone from changing it. If they're using Windoze, they need WinXP Pro (or maybe 2000) so they can create administrator accounts and user accounts, and they'll need to learn the difference. They will need to set up her account for her, installing all the software they will allow her to use, maybe a web browser and an e-mail client and NO chat programs. The account needs to be restricted from installing any software, and the administrator account should have a complex password the parents never give her for any reason. Then they need something like
Net-Nanny to block out everything they don't want her accessing. (Net Nanny is very hard to break on a properly configured system. It's possible, but not as simple as the previous program you mentioned.) This can be an expensive solution and time consuming, but it's a start.
If they're running WinXP Home or some earlier version of Windoze that doesn't allow you to really restrict user accounts, they may as well forget the software solution if the girl is a reasonably intelligent person or has access to techie friends who can help her out.