GrooveMonkee is a maker of fine midi clips. :-)
http://groovemonkee.com/collections/midi-loops I've used some of their stuff for a long time. If you browse for a bit on their site, they will give you a 25% off coupon on the right hand side if you let them send you junk mail. Their midi packs come designed for lots of different drum synths including Addictive Drums. They work great.
The midi clips I've gotten otherwise have come with Session Drummer Expansion Packs and Sonar itself. Addictive Drums comes with beats, and you can buy beat packs, but they don't let you use them with other drum synths without a considerable struggle. Addictive Drums is more about making money than helping you make music. For example, you can't pull in your own samples or record your own samples to use with Addictive Drums like you can with Session Drummer and most other drum synths I know.
Eli Krantzberg has some great videos on how to build up your own drum loops in Groove3.
http://elikrantzberg.com/Music_Theory.html