Saying there is not a lot 64-bit drivers shows you have no experience on the matter, the fact is there are 64-bit drivers for practically everything save some legacy hardware that is no longer supported by the hardware makers, in such cases one should not expect 64-bit drivers.
To date there are plenty of 64-bit applications and as already stated 32-bit apps work perfectly fine in a 64-bit O/S, there are no issues with software compatibility.
The OP is looking for a new family computer, a computer that most likely will not be upgraded for some time, if ever, and will need a very long service life, going 32-bit isn't going to do that. In his case, going 64-bit is the only answer as it will give him current compatibility as well as room for future growth.
Nothing screams "32-bit computing is dead" more then installing 4GB of RAM and NOT seeing all 4GB of RAM in Windows.
To the OP, computing is about progress and moving forward, the industry stops for no one. While one cannot always buy the latest or newest technologies, there are times buying last years gear can be great deals, the one truism is to completely avoid obsolete technology. Vista was supposed to be the transition stage to 64-bit, but it was so badly borked that it was pushed back to Windows 7. There is no going back.