Best machine or tools for removing and replacing grout 12 Dec 2008 13:33 EST

Hi.  We haven't done much in the way of removing and replacing grout.  Typically clean and clear seal or color seal.  We have a client who is determined to have the grout in two small bathrooms (2' tiles) replaced.  I am interested in any advice on the best method, tools or machinery to use to effectively remove the grout.  Also wondering what people charge for this (my knee jerk reaction is to charge twice what I would charge for cleaning and colorsealing).
Thanks so much.