Software?
I have not observed any software that will not run on win7. I have some very old software that runs fine without a single hiccup.
Even Corel Draw x3 will run fine on win 7 32 or 64 bit.
I see no benefit to using 64 bit over 32 bit. That is to 98% of the users on this board. This is my opinion after months of testing both in beta and in actual usage.
I just converted back to 32 bit win7 version.
There is very little software that takes advantage of the 64 bit side. That means your regular old 32 bit software will run as a 32 bit application no matter what. There are very few drivers operating under 64 bit. Almost all drivers are 32 bit.
Finally, no matter what version you use. Be sure to make a recovery/repair install disk ASAP after installing either version if the OS. You will need it.
Otherwise depending on win7 itself to do a repair install is asking for a nightmare.
Cleaning and compacting softwares for the registry and hard drives will run on 64 bit but some of you will suffer a machine that will not boot. There is no recovery other than a reinstall.
Beware.