I've just installed Windows 7 64-bit onto my desktop and all my software runs fine on it, the only problems I see with 64-bit is the really old software, perhaps seven or eight year old programs or older, most newer software is 64-bit compatible, it will run on a 64-bit machine even if it's 32-bit in nature. I have 49 programs listed in the "Programs Files (x86)" folder which is for 32-bit programs and half that in the Program Files folder which is for 64-bit programs.
You mentioned Nokia PC suite, I don't use it myself but I just had a look at the site for it and it lists Vista 32-bit and 64-bit so it's a pretty sure bet that one will work with Windows 7. As for any other software you're unsure about just go to the developers site and have a look for 64-bit compatibility.
64-bit is certainly the way to go and sooner or later you will probably have to switch, as 32-bit will go the same way 8 and 16 bit went.
I purchased the "Family Pack" Windows 7 upgrade which allows for installation onto 3 computers and best of all it comes with both versions of the OS, I have 64-bit on my desktop and 32-bit on my notebook as it doesn't support 64-bit and both versions are working fine.