Installing Adobe Reader X is a two-step process. First you download the installation package, and then you install Reader from that package file. You do not have to remove the older version of Reader before installing Reader X.
If you have trouble downloading Reader after trying the steps in this TechNote, try downloading the Reader installer directly by clicking this link: get.adobe.com/reader/direct. Select your operating system, language, and version, and then click Download Now. Follow the onscreen instructions to complete the download.
To see if other users are experiencing similar download and installation problems, visit the Reader user-to-user forum, or the Deployment & Installation forum on AcrobatUsers.com. Try posting your problem on the forums for interactive troubleshooting. When posting on forums, include your operating system and product version number.