Well in theory, search engines like Google are suppose to be able to read the text used in Flash Website, improving SEO somewhat. But in my experience, it has not developed to a point that is equal to a straight HTML site. In particular, if you are using xml files to provide text or other data to the Flash pages, I don't see Google indexing that text.
So as a backup, I would suggest using swfobject to place your Flash on the Web page. Then add plenty of regular HTML as "alt content" to descibe in great detail the graphic elements. Since most viewers will not see this "alt content" you can actually over do the descriptions and get in MORE unique phrases, descriptions, and text content, than if you were just using HTML.
So in effect, you can get your graphic elements displayed with Flash but the text data described in HTML. Is it more work? Yes, But if SEO is important to you, Flash of and by itself will not index as well as just HTML.
Here's an example of using "alt content" to descibe the products in much greater detail than what you actually see on the Flash page. First view the Web page, its just a simple .swf with a little text on it. Then view the source code and see the "alt content" that lies behind the Flash.:
For more info on swfobject:
Here's a little tip to measure exactly when and what gets indexed on your site. Create a unique word that cannot be found ANYWHERE on the Internet, something like "myuniquewordisdellamagestic"...can't be found anywhere on Google.
So include your special words in both your Flash file as well as the swfobject "alt content", using 2 unique words, to see which is indexed first. As soon as that word is indexed, it will appear top position, first page. So Google for it every so often, once it shows up you know that content has been indexed. See which gets indexed first, the text in Flash or the text in the "alt content".
I had one site where I used a complete text narration of a Flash video as the "alt content" and had the VIDEO (actually it's alt content) indexed within 4 hours. Now that's a case where using Flash PLUS alt content give a better WEb page than just the Flash alone or just the text narration alone. Best of both worlds I would say.