OPTOPMUX.DLL great sucess with the OLD ISA since like 1998 on Windows 2000 and XP, using the paramux driver package. Good hardware life as well. BTW we have found that more than one application can access the card at the same time using this driver package.
OPTOPCI.dll PCI-AC5 has worked fine on XP, how the hardware we recieved supposedly is from an earlier production run, and was a weak sister. I have several cards that show outputs being "stuck" on, my understanding is that this is a result of dirty power- but that is not my thing. Only one app can access card at one time (Which forced a redesign for us)
AC5Toolkit.dll PCI-AC5 under windows 7 so far has not been the best experience. Again we had these weak sister cards from some bastard production run, so we got BSODs on 4.0b. I got with tech support and worked with their person to provide a test environment to resolve. Took about a month which is reasonable I guess. Also because I guess the cards internally use negative true logic, this newest driver/DLL also required packed and unpacked calls to use negative true... (again design change however doable.) Also this DLL depends on windows 7 components and will not load on a windows XP computer. (again we had to redesign to load DLLs on demand) O and this version does appear to allow more than one application to grab a handle at the same time. (or maybe just doesn't fail)