Hi Christina,
Congratulations of getting your paperwork in the mail!! I know that is a huge step. I was so happy the day we did that. My husband and I attended the April 2003 orientation. There are so many happy families from our orientation already!
To answer your question... the book that you should read before orientation is the "Open Adoption Experience". I bought two books for both my husband and I to read. I thought I'd read it quickly, then hand it over, but that didn't happen. It is full of information!!
Also, if you are doing a lot of reading now, you might want to prepare a write up on the book. Texas requires waiting parents to read adoption related books and submit a book report on them.
You might also want to start collecting pictures of you and your hubby. If you don't have a lot, keep a camera with you and start shooting!
Have fun and really, enjoy this time!!
Cheers, Kim