My personal favorite is Bulk Rename Utility
Another good one is 1-4a Rename
Remember in renaming files BY DATE that you do indeed get a proper sort. [IE, you obviously don't want a name like File001_Oct 1, 2005.JPG or a name like File001_1Oct2005.]
For this reason, I recommend renamers that have a preview window so you can see/test your renaming before you commit. And, an "undo" option is also nice as well.
Too, you mayl need to consider file extensions as well, if they're not all the same, ie, JPEG and JPG may sort differently depending on your program, since some will take the extension into account. And here, you could conceivably wind up with two files with same basename but with different extensions? eg File001_10-10-2005.BMP & File001_10-10-2005.JPG. This could affect your sorting order, but maybe not enough to matter.
If you can't find one that works to your satisfaction from here [several good ones have already been listed], then I'd suggest trying alt.comp.freeware [Usenet]. First search for recommendations; if you don't find any relevant postings, then post your own. If you don't have Usenet access, you can search/post from groups.google.com for free. It's easy -- you can search quickly; if you want to post, you simply need an email address. To set up a Google Groups acc't takes but a minute or two.