XP 64 - applications installation issues

I am having a dickens of a time getting my new system installed with
everything from my old one. I had xp pro before, I now bought a 64 system
with xp pro 64 installed.

I did not understand the [Program Files (86)] and [Program Files] both being
on the system. I figured it was so old programs that ran on the old 386
systems went [Program Files (86)] and new programs went in the regular
[Program Files]

Except during install I just went with defaults and ended up with a number
of programs not working and breaking up between the two folders. I
uninstalled a couple of the old programs and told them to install to just the
[Program Files] and those worked.

I read a post about some programs can't read the [ ( ] or [ ) ] symbols in
command lines. It said to move make a new folder [Program Files x86], move
all the contents from the original one into this one, then edit the registry
values to point to this new file. I don't understand this need to have
different program file folders. It would seem to me to have just a different
name and not something else involved with that folder means that it's no
different than the regular [Program Files] folder on my system and it's just
a name with no specific hardware meaning.

I tried to install ACT by Sage into both folders and it still won't work.
The auto install feature don't work on the cd. According to documentation at
Sage 64 is not supported, but the work around was manual install and worked
for some customers. So I did the manual install to the default x86 folder
and it did not work. I tried to uninstall and it can't. I tried a manual
install to the [Program Files] folder and it still did not work as even in
the background it puts some things in this new [Program Files (x86)] folder.
Again, I can't uninstall it.

I also can't install my printer, HP9120, as they say it's not supported
either.

I'm really having a tough time about all this.

Is it possible to just [rename] the file name for this x86 folder? If not,
how do I go about changing registry values?

Any help or suggestions would be extremely appreciated!