Here are my experiences about using the SEO toolkit by the IIS team. I had a few sections I wanted to improve for search engines, using the SEO toolkit, it identified over 700 found errors. I've reduced to 187 individual items, of which is tied to a few articles that need some reformating. The articles will get touched up, which mostly are HTML markup. This was VERY helpful in identifying items on my website (www.iislogs.com)
Here is the list of things that were found.
Images did not have an ALT statement
Invalid HTML markup
Titles too long
Descriptions were missing
The page contains multiple canonical formats.
To correct the items, I downloaded my entire site locally, created a website solution within Visual Studio 2008. I did a find and replace in the entire solution. It was mostly making things consistent, putting items in lower case (a href and </a> for example). It helped to correct the HTML markup issues. The one way I keep formatting simple is using ASP.NET Master Pages. This can help keep the site maintenance to a minimum. I came from the days of multiple include files (both Classic ASP and ASCX files), so using a single file made adjusting the formatting simplier. The biggest thing on my site was images were missing the ALT tag. Once I fixed the easier errors, I focused on the larger ones. The tool found 408 ALT images missing, after adjusting my master page, the count was below 190. The SEO toolkit was helpful in identifying various problems. For issues, feel free to post in the forums at http://forums.iis.net/1162.aspx
Hope you find this helpful!
Microsoft MVP - IIS