You are using an obsolete version of Audacity.
The current version is Audacity 2.1.1 and is available here: Audacity ® | Free, open source, cross-platform audio software for multi-track recording and editing.
See here for system requirements: Audacity ® | Free, open source, cross-platform audio software for multi-track recording and editing.
See also: Important information for Windows XP users.