FeedDemon requires Windows XP, Windows Vista or Windows 7, with Internet Explorer 7 or later installed.
FeedDemon's install program is around 4MB, and a full install requires about 13MB on your hard drive. Extra space is also required for FeedDemon's database/cache, which is typically less than 50MB but may be larger depending on the amount of feeds you read.
A minimum of 1GB of RAM is recommended, but more RAM will be helpful if you subscribe to a lot of feeds or keep several pages open in FeedDemon's tabbed browser.
Note: If you have an older computer with 1GB of RAM or less, this FAQ entry provides some tips on optimizing FeedDemon to run smoothly on it.