There are a number of companies that offer software like this. Wild Ginger seems to be the brand that people like the best, the Pattern Master Boutique v3 product in particular (sometimes referred to as PMB or PMB3). Wild Ginger is known to have excellent customer service.

I'm also interested in buying pattern software and this is the product I'm considering. I am also interested in other sewist's experiences with pattern making software, all brands.

If you go to the Pattern Review website, (link after this paragraph) you can read a number of reviews of specific sewing experiences with this software (you may have to register with the site to read all the reviews).

http://sewing.patternreview.com/cgi-bin/search.pl?CompanyID=65&search=Search

Getting the measurements right is important, but once you have those and you've tested them in a sample muslin, it seems to be fairly easy to select a pattern and print it out. You do have to glue the printer sheets together. However, I've spent several evenings recently trying to alter a store-bought pattern, making multiple test garments, and I'm still not satisfied with my results. I would give up the use of so much time and my frustration and trade that for gluing paper together any day.

I believe there are several Yahoo groups devoted to sewing pattern software, and at least one for this product in particular.

CMC

Here is a link that might be useful: Wild Ginger