I have a 5 mP digital camera and the pictures saved in jpeg format are still between 700kb and 1mb. What i do is open the picture (double left click with the mouse) and then right click on the picture and select resize picture. I then choose the Medium (fits an 800x600 screen) or the small (fits a 640 x 480 screen)
As an example if the original Jpeg file is 850kb or bigger you'll need to use the small to get it a file size small enough to post here. anything under 850kb the medium will work
An 898kb file size resized to the small 640x480 brings the jpeg file size down to 101kb
That same size file 898kb resized to the medium 800x 600 brings the file size down to 148kb
Which if i'm not mistaken just under the max file size (150 KB) allowed here. Anyway thats how I resize mine. One more thing when you resize a picture file this way what you get is another copy of your picture in its new files size but the original remains exactly as it was in its original file size so your not going to mess up the original.