Finally, I have upgraded to WordPress 2.8.4 and installed Akismet seemingly successfully. Spam be gone! I also set up svn upgrading of WordPress so that I don’t have to do so many steps next time around.
For reference, I used:
http://codex.wordpress.org/WordPress_Backups to backup my stuff first
http://codex.wordpress.org/Upgrading_WordPress to do the upgrade
And then realizing that I could upgrade by svn, I used http://codex.wordpress.org/Installing/Updating_WordPress_with_Subversion. Very nice.
Update: It has been nearly 24 hours and I have gotten no spam comments to moderate in my inbox. Akismet caught 8 of them. Thank goodness. That was really annoying to see a new email every couple hours only to realize that it is spam. Kinda makes me really appreciate Gmail’s spam filter, even though it has screwed up somewhat majorly once.
Edit (2009-12-15):
To upgrade to the latest stable version of wordpress via svn, run the following command from /home/public/ (assuming 2.8.6 is the latest stable version):
svn sw http://core.svn.wordpress.org/tags/2.8.6/ .
and then go to http://www.whenbrainsfly.com/wp-admin/upgrade.php