Right now, realistically, there is not much of an advantage in 64 bit over 32 bit except that 64 bit can take advantage of and use more memory than 32 bit can. There is little, if any, noticeable difference in speed.
If you are into heavy graphics, photoshop editing, CAD, etc, 64 bit will make a difference. If you are just a routine user, the difference is nil. That will change as more programs are written for 64 bit. I am waiting on the browsers to be released in 64 bit before I upgrade.
If you are a routine user and your system is working well - if it ain't broke, don't fix it. On the other hand, 64 bit is the coming thing and by upgrading you will be ready for 64 bit programs.
I realize this was not much help.