I\'m looking for advice on a really small linux distro that I can run inside VirtualBox without killing the host system and that can also run the latest Sun/Oracle-Java. I don\'
If you want a binary distro you can go with vector or just ubuntu. You can configure either to run in a small amount of ram. I run ubuntu on virtualbox with the macbookpro as a host and it works just fine. I gave it 2GB or ram, but it would probably run fine in 256MB or less (your java needs might be higher). With ArchLinux you can get a really basic setup too, but it takes more work.
There are other choices if you really want to tweak the sytem. With Gentoo or Sabayon you can compile just what you need.
So it comes down to: if you really want to tweak the crap out of your linux install go with Arch. If you want to compile your system go with Gentoo. If you want to get up and running fast go with ubuntu. The great thing about linux and vms is if you dont like your choice you can just create another vm with another distro.