Dieffenbachia affects a cat's central nervous system. I saw somewhere that aloe vera is also poisonous, but my cat doesn't bother with that. I have Christmas Cacti as well, & I believe they are okay. For a list of plants poisonous to your cat & the side effects, check this website:
http://cats.about.com/cs/catmanageme...isonplants.htm
And for a complete list of plants & household products that are poisonous to cats, check out this site:
http://www.petcaretips.net/plants_poisonous_cats.html
As for the sewing room, just don't drop any needles. I did that once as a kid, & when our cat had to be taken to the vet, guess what he found in his stomach? Yep, a needle. My mother was not happy with me.
Enjoy your new pet's company; he will give much more than he receives!