Dear Carol, and Bruce,
You can’t reasonably expect Gpg4win and GpgOL to continue to support, free, a Microsoft product that is now a whole 12 years old and obsolete - Outlook 2003, for heaven’s sake! As Bernhard Reiter says, with great restraint, the work on it is being done on a shoestring, much of it by volunteers for the love of it, and I for one am extremely grateful. Werner Koch, the progenitor of GnuPG, is only now getting a living wage out of it (see http://www.worldcrunch.com/rss/tech-science/meet-edward-snowden-039-s-favorite-encryption-programmer/werner-koch-gnu-software-nsa-edward-snowden-facebook/c4s18234/#.VREyaeGgrqp ).
That said, there is a commercial variant of GpgOL called gpg4o which may solve your problems, at least for Outlook 2010 and up, produced by Giegerich and Partner (see http://www.giepa.de/products/gpg4o/?lang=en). It’s not cheap, starting at €47 for the Home and Student version, but it’s very good; I got it some time back on special offer, and it’s been very reliable.
Alternatively you could move to Thunderbird and the Lightning calendar extension as a replacement for Outlook, and use the (free) Enigmail encryption add-on, which is also excellent.
If you must stick with Outlook 2003, I suggest using the form of encryption that Outlook was designed to work with, namely S/MIME, for which you will need a personal email encryption certificate. You can get one free from CACert.org, or from Comodo I think. I wrote an article describing how to use Outlook or Windows Live Mail with S/MIME, which you can find here: http://www.davescomputertips.com/e-mail-encryption-encryption-encryption .
The 32-bit/64-bit issue is not particularly relevant. Not that many programs actually need to be compiled as 64-bit to work efficiently, as opposed to operating systems; 32-bit application code will be around for a long time yet.
Regards,
Martin Ward