Good text to speech programs?

I've been looking for a good text to speech program. I'm getting to impatient to read long bodies of text, as it hinders me from doing other things that I like to do with my computer. So listening to documents read to me sounds pretty convenient while I'm making textures or mapping or whatever.

I'm not too picky. I just need a program that doesn't have a limit on the amount of text I'll give it to read, and isn't very resource intensive. I do a lot of my mapping on my laptop, and I tried using Super Hal Reader, and doombuilder will slow to a crawl while speaking.

Any recommendations?

Acapela's pretty good, despite its glaring inability to say most sentences without making at least one horrible enunciation error. The British ones are just hilarious to me. :P

My Debian says that there is a text to speech plugin for Acroread.

You seriously use acroread in this day and age?