Doesn't this seem like an awful lot of effort just to install a new web browser? There is surely a simpler way
I've recently installed kubuntu to try it out and on its own its fine but trying to change anything (like installing anything) seems like a real headache.

Hi,

Installing things in ubuntu is usually easier than in windows. You just use synaptic, or adept, or apt-get to get the application(s) from the repositories. The problem is when the application is not in the repositories, but this is not common (it is really hard to find a linux application that is not available in the ubuntu repositories).

In your case this happens because you are using an "old" version of (K)ubuntu. For example, I'm using 7.04 and firefox 2 is installed by default (same in 7.10). Do you have any particular reason to keep using an older version of Ubuntu?

Indeed, installing things in ubuntu is so easy that you can upgrade from one version to the next one using only the update tools.

Firefox2 still isn't in the repos, because it depends on libraries that are still considered unstable. Since Ubuntu Dapper is all about stability, and Firefox 2 doesn't really contain vital features, but is not as stable as 1.5, they decided to keep the old version.
If you really really need firefox-2, then you might find help here:

http://ubuntuzilla.wiki.sourceforge.net/

Or here for the official instructions:

https://help.ubuntu.com/community/FirefoxNewVersion