here are some online sites to resize your pics.
http://www.shrinkpictures.com/
http://resizepic.com/
http://resizr.lord-lance.com/default.asp
or u can do it with a default windows program, like Paint, you open the image with paint and press CTRL+W and then put the percentage 50% with 50% and it will basiclly reduze the size by 50% or whatever value u put and then just save it.
or maybe if you download any image manipulator program.