Why wouldn’t my driver download under Vista?

My daughter got a Dell 1521 with Vista Home Premium. We tried to install her Epson CX6000 driver on it from www.epson.com, it failed to install every time (downloaded (took a couple of hours via RoadRunner), installed, asked for CD, and failed). I downloaded the files under my XP sytem (took under 2 minutes via a rural Cable Internet system), burned to CD, copied the files to CD, and installed cleanly from the CD on her Vista system. Why was the download so slow under Roadrunner/Vista and why the failure to install, when it worked so easy under our desperation attempt from XP?