Salem

So, I made an account, made sure i had the latest version of JAVA (x64) and downloaded the client. However, when I start the client, it just opens the console of a split second and then nothing happens and it closes down. What am I doing wrong?

There's a few possible things you can try:

Verify your Java installation after your installation to make sure it is working properly: http://www.java.com/en/download/installed.jsp (Make sure to have java in browser enabled. It should be if you've never installed java on that computer before. I'm assuming given the time passed since your post you have restarted your computer or closed the browser, but if you haven't, restart your browser(s) or the test will fail.)

Make sure the downloaded files aren't corrupt. Delete the salem.jnlp file (and any other files that may have been downloaded in the process) in Java's cache. (Instructions here: http://www.java.com/en/download/help/plugin_cache.xml)

You may have a security program blocking Java or Salem from running properly. You may need to test by turning off any virus protection, firewalls, or other security software you may have running. It may be the case that you need to open the appropriate ports for Salem, too, in any firewalls. This includes any home network router that has built in firewall firmware (most have some level of firewall as this is the nature of a router). Open ports TCP 1871 and UDP 1870.

Final note, and probably first thing you should try: use one of the third party clients. Kandarim's Latikai client and Ender's client are both trusted by the community. I mention this because the standard client isn't used much, and after a few days or weeks playing, nearly everyone switches. Not every is such a trusting soul, though, which is why I mention them last.