for me to resize pics without downloading anything...
www.imageshack.us
upload your picture,
click the box next to rezie
select the size in the drop down
then click upload
youll get this window full of links
, choose the one with the
[img] or [url] <-- tag looking like this in the beginning
and then post it in your message..
if you resized it to be 800 x 600 then click on the thumbnail or your picture to the right of the page and then saveas, and there you will get your resized picture
hope that helps