One of the best solutions for keeping kitty from scratching you and your stuff are rubber nail caps.
The lovely Nobu below is modeling a pretty sky blue set from Soft Paws. They were developed by a veterinarian and available since 1990. The kit includes 40 nail caps, 2 tubes of adhesive (the same type of adhesive used in veterinary procedures) and tips and instructions. Each set lasts about 4-6 weeks so it's about a 4-6 month supply.
They come in a variety of sizes and colors, and are even made for dogs. The cat version is only $18.95
Buy them here (check the right size for your cat.)
See here for step-by-step instructions on how to apply them.