I take the lazy approach of dropping the gif into a predefined file on the server, then using an <img src='xxx.gif'> tag. There is no way of doing it inline. If you're generating many of these images, it is usual to generate a name automatically using a random number combined with a date/time element, then use each run of the script to clear up images from previous runs of the same script, such as clearing any image older than ten minutes old.

I haven't checked the memory usage, but I'm using this on an internal server, and it doesn't seem to leak memory, as the COM object should(?) drop all of its' memory at the end of the script.