Advice for "crossgrading" from 32 bit F11 to x64 ?

[Linuxguy123]

I do a lot of photo processing... things like generating 200 jpgs from
raw files at one go.   My laptop has 4GB of RAM but is currently only
using 3GB because I am running a 32 bit kernel. 

uname -a
Linux localhost.localdomain 2.6.30.8-64.fc11.i586 #1 SMP Fri Sep 25
04:30:19 EDT 2009 i686 i686 i386 GNU/Linux

Sooner or later I want to upgrade to a 64 bit kernel and 8 GB of RAM.
Other than this article, I can't find any information on the subject.

http://www.linux.com/archive/feature/123800

I am looking to do the upgrade WITHOUT reinstalling Fedora.  I've done
enough re installations in the past to know that I don't want to go
there.

Has anyone done crossgraded from 32 to 64 bit ?  What advice do you have
to offer ?

Thanks