I would 1st ask OF or Mods to remove the link to a possible trojan source... they're are people who click on any link to just link from boredom, and then moan about it.
'XP' from among the Microshaft monopolies products is more likely the best for IL2, or used as the program compatability setting.
I unfortunately have only ever had a XP as a O/S I understand somewhat limitedly (Currently; Media Edition + Service Pack 3 = XP Profesional?). Fortunately, I haven't gone Vista or 7 cos' it's taken Microshit 8+ years to get XP working, let alone the stories I've heard about with Vista, more than of 7's.
I wish I could uninstall XP-SP3 without being able to totally reformat & reinstall because of my Duff brand laptop it's repair & reinstallation discs are useless. Unless you have specific problems solved by it, I wouldn't go XP-SP3 if you can help it, afaik, SP2 is still has current windows updates.
It did make my XP a little more quirky - random occasional temporary freezing, problems, reactivating or changing settings/options of Outlook and Internet Explorer for their hidden processes, & their unneeded internet functions not requested by myself or my system requirements - settings to minimise 'Windows coded-in back door' weaknesses to the internet that I had set. Generally for me, it's almost as bug free as SP2 was. Oh, you cannot uninstall Internet Explorer or Outlook, as Wierdows needs them to work!
Although service updates are sorting problems, and I never had the serious problems of some XP Pro users had with SP3 had when it was released 3+ years ago, which were akin to Vista's total or blue screen crashing. I'm still not sure if XP Pro Edition (SP2) is now stable/compatable with SP3.