Which Free version of READER should I use?

You can go for Adobe Reader 8.0 as it is liable, takes only 20.81MB of space on the Hard Disk as compared to 9 which take its double which is 40.1 MB and after installing this don't update the Reader as you'll then get the Adobe 9.0. You can download the Adobe Reader 8.0 from below mentioned link. However if you want to get the previous versions as well you can choose there as per your choice and the size as previous versions have smaller sizes as well. On the right hand side of the Webpage in a Green Panel.