Currently installing Windows XP on an old, 17in Dell monster laptop from about 2006. It's got a massive 2gB of RAM, 250gB of spinning rust, and an unbelievably powerful Core2 Duo t7400. Oh, and how could I forget the awesome Nvidia Geforce 7900 GPU, and an actually quite nice 1920×1200 screen. Gunna see how many cool, old pieces of software I can get working.
@Lwasserman No, but it does have a 56k modem. I do have plenty of machines with serial and even parallel ports. My mother's pretty boring 2011 HP still has one, along with a modem, and I even have a black Dell laptop from the late 90s with no modern USB ports anywhere, or even a CD drive. That runs Windows 98, but with a lack of assistive technologies for Win9x, (I'm blind and use a screen reader) I haven't done much with it yet.