Amazon, welcome, this is one of my bugbears too. I quite agree, philanthropy it is not, but I see why mumsnet have accepted the Persil advertising. I don't think it's the same as schools accepting corporate funding and I just ignore it. If Persil want to think I look at it every time I click on this site and it means mumsnet get some revenue then OK, I can live with it. I don't buy Persil though and wouldn't solely as a result of advertising or promotional tokens.
Doormat, if schools are underfunded (and they are) we should blame the government and local authority spending IMO, rather than letting commercial organisations pretend to help by offering computers or books in exchange for product loyalty. And these token promotions are marketing to kids. The idea, I assume, is to encourage brand recognition and loyalty in children and parents and to drive additional sales (and profit).
Soupdragon, you say "...what's the problem? It's not as if they (or anyone else) had to pay £220,000 for a new computer." Well, surely the consumer paid £220,000 (if that's the figure) for the computer! There's no way these companies are donating the equipment or the cash: they will have built the promotion cost into pricing and it will have been more than covered by increased profitability.
Wills, exactly on the Sunny D, Walkers etc front. There was an interesting article a while ago about News International and their (legal) avoidance of corporation tax i.e at the usual rate their contribution would have netted the exchequer £92m in one tax year. This contribution could have bought lots of books for schools (I know, it might not have been spent that way but) but Newscorp would rather books for schools were 'bought' via token promotions dependent on buying a Murdoch paper. There's an article on the subject here
Amazon, have you read Fast Food Nation? It's an interesting read with a scary section on the subject of advertising to children, especially in schools. There was a brief thread about it a while ago here
I really don't think most parents care much about this though, I think most don't think about it. They may choose to go with the promotion without really considering the issues involved and many are prepared to do anything (except lobby their MP, get involved in local politics, complain about it, stuff that might actually help, eventually) to help cash strapped schools without really thinking through the ulterior motives of the companies concerned.