NYJ, it is best to only ask in one spot or even start your own thread. I answered this in another thread where you asked but here is a copy of my reply:
4GB is fine for 32 or 64 bit, so RAM won't be an issue. However, you must make sure your laptop is capable of running 64-bit because not all computers can (ie yes it depends on your laptop specs). Also, assuming it does allow 64bit, you will need to get the 64bit drivers (the 32bit drivers you have now will NOT work) and have them available on CD or flashdrive. If you do not have a copy of the 64bit W7 you will need to download a copy from Microsoft and burn it to a DVD or put it on a flashdrive. Also switching from 32 to 64 bit requires a complete reinstall, which means user accounts must be backed up or recreated, all your data (documents, pictures, videos, music) must be backed up and then restored on the fresh install, and all software must be reinstalled including any factory installed programs (if you do not have a disk of these you will want to download them from the manufacturer). For any programs that require product keys, make sure you have them written down before you format the harddrive (a freeware program like SIW will show you the product keys of many programs installed on your computer).