Lucasfilm/arts put a great deal of effort into maintaining continuity across all facets and media that the Star Wars franchise encompasses, but I believe a great deal of the games are considered lower level canon at best, with some of the newer more story driven games such as The Force Unleashed considered quite a bit higher, perhaps on par with the novels. There was a table released in an article somewhere regarding Lucasfilm Licensing which actually had a table depicting the various levels of Star Wars canon, with the movies obviously at the top of the list and I think a letter grade which designated the levels of canon beneath. video games were pretty low as I recall.