We bought AC to replace a schedule and billing program that was DOS based. (You remember DOS don't you?) Didn't try to get AC to run on the Windows '98 machines, but kept them for a few months as a station to look up old chart numbers on. Currently have 2 very old servors, (to be replaced this month) and 14 PC's, 4 laptops and 3 "thin clients" (what I call a dumb terminal). Our network is all wrong, but is gradually getting into shape for the current job. Everything is on XP-pro, except one laptop that we tried on Vista, (hey, I saved $100.00) and then we paid a bunch more to have XP-Pro installed on it. AC works on Vista OK, but Vista doesn't work so good on Vista!