The current version for Linux should be
tor-browser-linux32-3.5_en-US.tar.xz for the 32-bit version (replace 32 with 64 for the 64-bit version), so it sounds like you have it right.
.tar.xz means that you have a tar file that has been compressed using the xz method. You can think of this as being similar to downloading a zip file and extracting that the same way. The Tor Project use
.zip files for Mac releases and
.tar.xz files for Linux.
Ubuntu does have Tor releases in their "Universe" repository, and this may be easier to install, but it often lags behind the official Tor Project releases so may have unpatched security problems. You're also unable to verify the package signature when downloading over APT.