kaled - 4:02 pm on Apr 16, 2008 (gmt 0) Kaled.
Clearly, you are not a programmer. I could say more but I won't.
Hopefully this whole debacle will teach software vendors to write proper cross platform code.
Direct port access won't work in any version of windows based on NT - that includes XP. The only issue Vista has in this regard is that (I think) it requires all device drivers to be signed. All hardware access must pass through a device driver. That's true of any operating system that permits (preemptive) multi-tasking, otherwise two programs might try to access the same hardware at the same time.
Even simple things like direct port access for control systems are so constrained in Vista that the only answer is to retain XP indefinitely.