google indexing every single wordpress page?

Im sure this is bad for my rankings? If i type site:http://www.mydomain.com on search

i get so many pages within my domain, a most of them are not true pages, and alot of 404 pages, and other links are for example:

/wp-content/uploads/2012/05/
plugins/wp-e-commerce/wpsc-theme/

etc and a bunch of similar links.

Why is google pulling all of these random links from my website? This isn't the case when I look at other websites.

Well have you been adding and deleting a lot of pages? Make sure whenever you make a change to your site that you use a plugin like "Google XML" and re submit your feed to google. This will help make sure that your pages that you want are there, and ones that you don't want aren't.

Use a WP seo plugin (like all in one seo pack), most of them will take care to automatically place restrictions in .htaccess of various folders and files that doesn't need to bee indexed. Or, you can restrict their access manually in .htaccess.

I don't know for sure how this affects rankings, but it doesn't look right in search results.