Dave,
I just posted a picture and part of the secret of getting a larger picture accepted is to adjust the amount of compression in your jpg file.
I first tried doing a 640x480 file which was well over 100k in size and larger than would be accepted. I reduced the size a bit to 600x450 but it was still too large, until I adjusted the amount of file compression that was being used. It then dropped down to 74k in size.
I've attached the same picture to this message but resized it to 640x480 and still got the file under the 97k size limit.
So I guess the trick is the amount of compression you're using in your jpeg files.