how do I run x86_64 programs on fc3 i386?

[sean darcy]

I have fc3 i386 on an amd64 machine. I don't want to move the install to 
x86_64, but I do want to run  occasional x86_64 programs. When I do though I 
get:

bash: /usr/local/bin/myprog: cannot execute binary file

Should I install x86_64 bash? Will that mess up my i386 programs?

If I did reinstall x86_64, will I have the same problem running i386 
programs?

sean