When using today's state of the art data retrieval software to recover deleted files, vista is not a requirement. Even the most recent data retrieval software can work with computers using very old operating systems like Windows XP or Windows 2000. Some people today still have computers that use the old Windows 98! These people as well, can rest assured that they can recover deleted files, vista or not.
But really, whatever version of whatever operating system you use is of very little consequence, as data is all "lost" and restored the same way. It all has to do with how your hard drive crunches up bits of data to store and even hide it all away in its little hiding places. The fact of the matter is that data never really leaves your system - it always stays on your hard drive in one form or another, and is thusly always retrievable. Software tools used for data retrieval can recover deleted files vista or not, it generally makes no difference.
There do exist some data retrieval tools that when used to recover deleted files, vista or other operating systems may not work, but these are usually of the type made years ago, and are often freeware. Today's data retrieval software can recover deleted files, vista or Windows 98, no problem at all. It's all in where you find it, and how old the software you find may be. Use today's data retrieval software, and you'll simply have no need for any worries at all.