What type of Ethernet cable should I use?

Hi all. I've been having a lot of Wi-Fi connection issues on my Blu-ray player, while streaming netflix, which is upstairs from where the router is located (I have no issues at all streaming wirelessly to my PS3, which is on the same level as the router), so I thought I would try a wired connection and see if that will help. It's been many years since I last bought an Ethernet cable and was unsure of what type I should I get.
I need approx. 50 feet and I see several different types available online for roughly the same $10-20 price range: Cat5e, Cat6, Cat6a, Cat6e and Cat7. So my question is, what type of cable should I buy? Does it really matter? I read that Cat6 is better for longer distances, but I doubt that matters much in home networking.

My router is a Linksys WRT54GS. Thanks =)