Welcome to JM! I'm part of the "older first time mom" club too - I had my son in Jan '08 the day after my 38th birthday.
Congratulations on your pregnancy - you should check out the Jan '10 Due Date Club where you'll find other moms expecting at around the same time as you. I made some great friendships in my DDC and highly recommend it.
I'm very sorry for your two previous losses - I've had 3 miscarriages (2 before my son and 1 after), so I can relate to how difficult it can be to really relax and enjoy a pregnancy, but do try because before you know it, you'll have a baby in your arms and you'll need that nursery.