The issue of whether the sevice that enables the sharing of files is itself illegal is still moot, both in the USA and the UK, so far (I think). I prefer the Sony Betamax case as precedent in the USA, and the Amstrad double-header case in the UK, both of which hold that the means is not illegal so long as it may be used legally. The main question of the present litigation is, if the overwhelming use of a means is illegal, is the provider of the means liable for the infringemnts of others?
But if the RIAA or BPI sues you, the cost is a drop in the ocean for them but possibly a fortune for you.
In the UK the principal enforcers of the (rarer) criminal sanctions in respect of copyright enforcement are the local Trading Standards, and getting them interested is hard.
Kazaa Lite and Soulseek involve a lot less malware, if your daughter cannot be reformed, at least let her sin with prophylaxis.