The reason it doesn't work is because of how your database is configured. 2 and 3-letter words such as "all", "in" and "one" are not indexed by your database and therefore are not used in searches performed on your site.
TigerDirect is going to be using a much more configurable and powerful search engine than ships with the default WordPress.
If you want 2 and 3-letter words indexed in your database, you'll need to ask your webhost if they can make that change for you. However, it's an unusual request and they might not do it.
You can see that 4-letter words are indexed by your database because a search for "dell computer" does return accurate results.