Fiona, after reading your reply I went in search (online) for what I had downloaded, + suspect it's the same d/l silkstone has just posted a link for. It's Epson EasyPrint that I downloaded, which is not actually a Vista driver, although it will work in Vista. It is a utility which enables some prog's (particularly Adobe Photoshop) to access the printer driver more directly than in the normal course of events (i.e. via Properties).
On a re-think, when I say "I got the R300 to work ok" it didn't work "ok", but I put this down to the printer/cheap inks rather than Vista, as the quality of prints is just as crap on my XP machine