Pretty much any Linux distribution will do, as they all ship with pretty much the same software.
If you just want to continue programming Java, and don't care for anything else, install Ubuntu, install Eclipse from the repository, and you're all set.
If, however, you want to learn about the OS, too, and maybe even see a few different interfaces than what you're used to (many of them much more user friendly than anything MS shipped recently), try Gentoo (as Corona mentioned), Debian or Slackware.
Gentoo: A coders dream, as all software is installed from source, which means that all development APIs are instantly available, and all software is optimized to your system. But the learning curve is very steep
Debian: Rock-solid. Has one of the (IMO) best package management systems, and probably the largest package pool of all distros. Steep learning curve, but nothing extreme.
Slackware: One of the oldest distributions (and I think the oldest still around). All software is pretty much vanilla, but there's no dependency tracking. Quite steep learning curve, too.
Or you could use something different, like BSD or Solaris. Take a look at
DistroWatch.com and try a few.