this is 1 of them odd situations where the game wont work on 64bit. it just doesnt support it at all.
dual booting with 32 bit and 64 bit will also bring its own problems, if you use viata or win7 as the high precision event timer in bios needs to match the running o.s. (set it to 32bit for 32bit and 64 for 64bit or the system will be unstable).
running in compatibility mode wont help either.
your only option is dual boot with xp 32 bit as (hpet) mode has no effect on that o.s. so you can leave it on 64bit for your win 7 but this means you will have to use a different hdd as the partition table and mft are different to vista and win 7.
theres no such thing as easy when it comes to windows