Notepad in recent versions of Windows should be able to save UTF-8 files as well, IIRC. It should be as an option in the file type drop-down menu.
With regards to encodings and accented characters, plain old IPTC was specified only for 7-bit ASCII, as Kirk noted, that means, only "normal" characters. You can of course write into it using other encodings, but there is no way in plain old IPTC to note which encoding has been used. Therefore, using plain old IPTC with any other languages then English is not recommended. Every and each software can expect some specific encoding used in plain old IPTC, and can hiccup if there are characters in another encoding (in the best scenario, just replace them with ?s). Only IPTC/XMP allows for specification of encoding or even UTF usage. Because of the IPTC limitation, most European newspapers and agencies developed their own workarounds before the advent of XMP, which can still cause a mess, as there are lots of legacy software backends in the publishing business, that still expect the IPTC with some local encoding used. Hermes, one of the most used newspaper publishing software, only accepts XMP in more recent versions, which are not always deployed in all newspapers yet because of the upgrade/IT costs.
Therefore, if your client needs specific encoding, you should contact him/her to find out whether they accept XMP, and if not, nudge them towards it, and if it's not feasible for them to upgrade their software, find out which encoding they need the captions in.
Yes, it can be a mess. In an ideal world, everybody would be using XMP with Unicode...
Fortunately, Photomechanic can let you select any encoding even for plain old IPTC, which literally saved my a** many times.