5 weeks pregnant and have some questions?

I've asked a few questions prior but I still have a few more. I just found out I was pregnant after TTC for six months! I'm 5 weeks pregnant and due around August 17, 2009. This is my first pregnancy and I'm nervous but so happy! I had a question about exercising and being pregnant. I use to going to the gym 4-5 days a week and do 45 min of hard cardio. What should I be doing now? Should I just do moderate cardio on the treadmill or eliptical for 20 min or so? My doctor's appt is not until Jan 15 (they want to wait until I'm 8-19 weeks so they can do a sonogram). If anybody can help me with this please do! Thanks