Languages: Many languages including English, German, French, Spanish, Portuguese, Italian, Polish, Traditional Chinese and Chinese Simplified.
Compatibility: Windows 98 upwards
License: Freeware.
Author's description:

RSSOwl is a free and powerful news feed reader. RSSOwl lets you gather, organize and search news in a convenient, easy to use interface with endless flexibility.

My opinion: Easy to use and has plenty of features.
Website: http://www.rssowl.org
Download page: http://www.rssowl.org/download

Yeah very powerful !!! I am using this - it already has a portable version (zipped download).