How would I setup a Cisco 1841 router to export data to Netflow Analyzer on my computer?
Here's a great doc from Cisco
Also try our NetFlow config free tool - I have not tried it myself on an 1800 but it works on most routers.
It should work, we've got quite a few 1841's reporting to us. I would guess your version of IOS would be the only thing holding you back.