A Linux live CD is a great idea for anybody that wants to check their email safely. You don't have to worry about viruses or adware from attachments or shady sites.
Maybe it's just me, but worrying about stuff like packet sniffers seems to be a bit overboard. If you've got enemies in the wrong places who want your info, they'll get it some way or another. Can you hear the black helicopters circling overhead yet?
If you're really paranoid, use your DSL connection to download a live CD of
Anonym.OS.
Some of the others here might have some different ideas, or might even tell you not to listen to me.
My 2 cents,
Baltika