How to get 32 bit packages installed in 64 bit ubuntu
I use the 64 bit version of Ubuntu as I have an AMD 64 bit processor on my PC. I’m not sure how drastic a difference it makes in day to day tasks but I figure since I have the architecture it’s nice to take advantage of it. In any case, there are some programs that don’t have a 64 bit version. If you attempt to install one you may get a message like:
package architecture (i386) does not match system (amd64)
If you have a .deb file you can enter this:
sudo dpkg -i --force-architecture packagename_i386.deb
To force install it. If you don’t have a .deb file read on….
Just because it’s 32 bit doesn’t mean you can’t use it. There’s another great Ubuntu forum post of the topic here which describes some of the ways to accomplish getting various software to work. Additionally Automatix will install some 32-bit programs for you. The 32 bit program that I use most is SwiftFox as I can configure some of the web plugins like flash to work with it. There is no 64 bit flash plugin available so you can either use a 32 bit browser or use some plugin managers like nspluginwrapper.
It’s very rare that I find I just can’t get something to install or work under 64 bit Ubuntu.

I installed the i386 version of Opera with –force-architecture, and it installed, but I can’t run it.
I’d like to be able to either use it or uninstall it, but I don’t know how to do either.