Congratulations. That is so great.
I was obese when I was pregnant with both of mine. I was 292 when I got PG with Lilly and 317 when I got preggo with William. Lilly's pg I wasn't classified as high risk because of my weight. It was actually a "normal" pregnancy. I had her c-section but only because she was stuck on my pelvic bone and wouldn't come down. William was classified as high risk but only because I had gestational diabetes. At my first appt. weighing in at 317, the doc wasn't concerned about my weight. He just told me that if I went over 350 pounds I would have to be transferred to a hospital in OKC because their operating tables only go up to 350. That sure scared me enough and I actually lost 13 pounds before delivering him 3 weeks early.
If you want some great support for being overweight and pregnant here is a great message board.
http://www.pregnancy.org/phpBB2/viewforum.php?f=36