One weakness I have discovered about this is that it does record a session ID in the URL, which if someone were to copy and paste, it would allow them to access the site.

I'm not worried about it for my purposes, but there must be a more secure way!

I'm pretty sure there is a way to turn that off actually, because on the pages I've done with it the session ID doesn't show up. I'll look it up for ya tho.
You're welcome by the way. Have a good one. If you ever need anything else feel free to look me up.

**EDIT**
Seems like it only adds the session to the url if you have cookies disabled.

Actually cookies are enabled on my PC - however, I will look it up as well on PHP.net

You could also try and use cookies by themselves, instead of through sessions.

Create the cookie when the user registers, then read the cookie whenever you need the hidden info.

I see what you're saying... but what if a user decided to delete his cookies? Then wouldn't he need to reregister??

That's correct. At the same time you would encounter a similar problem with using sessions, since it tends to employe cookies as well. You don't directly "see" it, but most configurations do.

On the other hand, this won't be much of a problem for the type of application you are trying to develop. The idea is that a user logs and then his/hers info is carried between the pages he/she visits. If they leave the site and return later, with cookies, you could make it so the person's info is remembered. Or you can make it expire like with a session. If they delete their cookies, then it doesn't matter, since you'd just make them login again, just like what would need to happen with sessions.

In the end it doesn't matter much...

right... for my current project what I have is sufficient...but I still would like to know what the best thing to do is for when I launch a site that needs to be totally secure!