Should I stop

[Tydemneo]

I have started dieting and now purchased the wii game Active 2 with the heart monitor. I am very unfit and am about 150lbs over weight.
I started with the warm up and the lowest exercise routine, I lost 283 calories and my heart rate was 145 while exercising running etc.
All of a sudden I felt like I was going to pass out. I felt really sick and grabbed a bucket but wasn't . I felt really ill I lied down for approx 1/2 hour and I felt all right.
I had no chest pains or very fast heart beat. Is it ok to carry on and is this normal.