I think that there are some situations where the website should pay. Particularly when they are using up users allotment sending advertising to their browser. Windows Update, Virus signatures and other security updates, should be applied without impacting users allotment or website.
There should be three classes of data.
1) No usage charged to website or subscriber for security, virus signature updates and patches including Windows Update.
2) User paid for accessing selected websites for traditional browsing.
3) Advertiser paid for sending advertisements to your browser whether requested or automatically downloaded.
After all, any solicitor wanting to make a sales pitch does not make collect calls or send advertisements postage due, why should internet advertisers, be any different. There is a law against sending junk faxes because the receiver has to incur the cost of ink and paper, why not the same rules for internet advertising. On the other hand if a user wants to download Open Office the usage for the download should be charged against my allotment.