Urusei Yatsura movies

[chronoclast]

I need some help with this. I've been wanting to see Urusei Yatsura, mostly because of Mamoru Oshii, but the tv series is just way too much for me to try to buy. So that brings me to the movies. Is it necessary to see the tv series with any of them or are they self contained? I'm most interested in the first two that Oshii directed, especially due to how well regarded Beautiful Dreamer is, but I'd like to know if it would be worth picking up the latter four too?