The problem is Windows Genuine Advantage required for XP SP3. WGA requires an active internet connection in order to validate your copy of Windows. Otherwise, you're SOL. All my Windows are volume-licenses or retail. The *HUGE* problem in that (which affects the basic functionality of Vista and, potentially, Windows 7, and is why I cannot use them for internal machines) is that
NOT EVERYBODY RUNS MACHINES WITH A NETWORK/INTERNET CONNECTION! Half of my dozen machines are not internet-enabled, for a variety of reasons; I run some offline machines, (as do many of my clients, as I am a security consultant) also do not run internet-enabled machines where security is of critical importance. I only run internet-enabled machines where there is a need to do so (email, web browsing, some stages of binary analysis, etc.) Internet is not a given, which some Os developers seem to think.
Not that TS2009 is of critical importance. It's just that Aurea has effectively shut me out of the development of TS2009-related products by binding me to a Service Pack that I cannot use. If there is some kind of patch then great. Otherwise, it precludes my purchase and development of TS2009 products. I am at least happy that I found out now before buying the sim. If TS2006 is a reasonable development platform and can give decent renderings of content, then I will stick to development for it. But I will absolutely not re-invent the wheel for another platform 2 or 3 years down the road; I just want a platform I can stick with and with which I can commit to for what likely will at least be a large-scale development of Philadelphia-area routes if not much more.*
*As a Flight Simulator 4 user, I developed many dozens of scenery sets back in the day, being more interested in developing airports and cityscapes than the simulation itself. I can only hope Trainz, whatever version it may be, is as enjoyable in which to create content. But I'm not willing to go back to square one with every new release.