http://pc.gamespy.com/pc/hearts-of-iron-platinum/568123p1.html
Is it really a 4 of 5 with all the patches now? Did they ever fix the AI?
The fan-made “CORE” mod (http://hoi.coremod.org/) which is included with HOI Platinum fixes most if not all of the egregious AI issues and adds a bajillion EU2-style events which make playing it roughly similar to playing a WW2 game (wording intentional). It’s worth a try, although I wouldn’t bother with the vanilla version.
I always wanted to play this game cooperatively with some others. Having “allies” that were just useless, noncooperative or ineffective made the game that much worse.
Art imitating life :P