>>I am scheduled to give a lecture on XML usage next wednesday evening (Sep 6)
>I would like to attend, but my two cents would be that I could put together time for 1 or if I am lucky 2 sessions, but I doubt if I could attend 3.

You are more than welcome to attend whichever ones you can make- attending the second or third session will not require that you have attended the previous lectures, but some of the material will use what the previous ones covered.