You could try using the 2 plugins from GaMerZ. They shouldn't be too hard to join together. Of course, I mean the WP 1.2 Stats and WP 1.2 User Online, located here: http://www.lesterchan.net/portfolio/programming.php (forgive me for not making it a clicky link. I have no idea where the backtics should go when formatting a link, and I don't want to screw the page up).
I'm currently running a slightly modified version of the stats on my site (took out the tabels and trimmed out some of the display options), and I have used the Users Online plugin in the past. Both work very well.
Hope that helped a bit! :)