the wxwidgets version of Rockbox Utility is outdated and will soon get replaced by a new, Qt4 based version. Currently there are no binaries around (but I expect that we'll start distributing binaries soonish) so you'd need to build it yourself. In case you want to try this, grab the rbutil module from svn, go to the folder rbutil/rbutilqt and run qmake-qt4 && make.
(Of course you can still use the old version

)