Depends what your language is
I think they have done (or are doing) a French Translation over at vBulletin-fr.org
Many of the phrases were translated to French for 2.0 (which are still pretty valid). However if you want a complete (and easy) way to translate than just edit the install file. There you will see all the english phrases in an array. Leave all the variable and such the same... just change the text and then install and its done!
If you do translate - let me have your install script back and I will roll up the translation into the next install file.