gaim print size too small

You could install gaim-extendedprefs plugin. It manages font size easily.

Luca
  I thankyou for the information in your reply to ticket #4007.
  Having been using "windows" for so long I am finding it difficult to get used to linux operation although they are very similar. I "googled" and downloaded the extendedprefs file you suggested but as with most of the other files I have downloaded "aMSN 0.96 & 0.95" they download but I cant seem to get them to operate. I may well be pushing the wrong buttons. I have only just changed from ubuntu 6.06 where I had no such trouble.
  I am still running a windows computer which I plan on making reduntant if linux proves to be a better overall system.
  Tony

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Such plugin is present in Ubuntu repositories (Universe actually). Be sure to have it enabled, see https://help.ubuntu.com/community/Repositories for further help.
Once completed this step, search for gaim-extendedprefs in Synaptic (the application you just started to manage repositories) and install it by right-clicking on it and choosing Install option.
Now, open gaim. You will see its icon in tray (it is situated near clock applet). Right-click on it and choose Plugins. Select Extended preferences from the list shown and click on Configure. Now you should be able to set a better font size.