RoHS is not a world wide standard. It is an EU standard (Note: There are a few other nations that have also implimented the EU standard). If a manufacturer wants to sell electrical products in the European market place the product must be RoHS compliant. The problem with RoHS compliance is that the materials used in the manufacturing of these electrical components form dendritic grain cells (non uniform, spike like structures. These structures alter (distort) electrical flow through cables, wires, and solder. In some electrical devices this does not matter, in other devices it makes a great deal of difference (Note: Military and hosital electrical equipment is exempt from RoHS. They are exempt from RoHS because the circuits created with RoHS materials are not reliable). Perhaps some manufacturer of high end equipment would like to weigh in on this and describe the sonic differences in using RoHs compliant materials vs lead, tin, and silver.
Are most PC's ROHS now compliant?
The only one I know of is the Cardas that is available through Merlin.