"For example, there is no reason why your copy of Solitaire should be able to browse through your tax records and send interesting tidbits to organized criminals in Russia. Today's generation of antivirus, antispyware programs work by having a list of all these bad programs and scanning for them. The OLPC approach is to simply deny your Solitare program from being able to access the network or browse your files. Why should it need those capabilities, anyway?"
LINK to article about the security systems on the OLPCs.