Just FYI, 64bit is not automatically faster than 32bit so what the salesperson told you isn't exactly true, but 64-bit would be faster for programs optimized to use it. Also if you ran any old software which is 16-bit, that will not run natively on a 64-bit machine, but it is very unlikely you still run any 16-bit software unless it is very old games.
That being said, if you have 3GB of RAM or more then there is very little reason to want 32bit any more. It sounds like you may need to download the latest version of Skype, because it will definitely run on a 64-bit machine.
Like David mentioned, provide us with a list of software, including version, that you cannot get to run on W7-64bit and we'll check it over.
Now one thing that is quite different between 32 & 64bit are the drivers, so you will want to download the 64-bit drivers for your peripherals, including your printer. But those drivers will be free to download from the manufacturers website so that is easily resolved.