I use Irfanview to do this click here then open you pic up in irfanview then select save as from the file menu it will save your pic as a jpeg but with the size cut down,just dont send the wrong 1 lol.
I have Paint Shop Pro 8. To reduce the image size click on 'Image' and then 'Resize' and enter the required value in 'Pixel dimensions' - I enter around 700 for width. Make sure that there is a tick in the 'Lock Aspect ratio' box to keep same proportations.
Open PSP and go to 'Image' then go down to resize, then just follow the on screen instructions, worth knowing that its better to resize by % rates rather than pixels size. If your not happ with the new size then just go back and change it again, till you get it right. I would also save the new image as a different file name so as not to lose the original.