"upgrade to 64bit" You have to do a clean install if going from 32bit to 64bit. You will lose all data on the harddrive and have to reinstall all your extra software programs. I believe 95% of 32bit programs will run okay on 64bit.
Run the advisor and it will tell you what will be okay. There are two tabs info for 32bit and info for 64bit, so you can compare what you have on 32bit with what will be okay on 64bit.
http://windows.microsoft.com/en-GB/windows/downloads/upgrade-advisor (info page with link to download)
and here you can check individual programs etc for compatibility