Linux is well known to run on all kinds of hardware from the oldest machines to the worlds super computers, and am always coming across friends that have older machines with only half a gig of RAM but most modern desktops recommend at least one gig of RAM. While it might not cost much to upgrade, I still think that a PC can still be comfortably usable without upgrading.
gPodder downloads free audio and video content (podcasts) for you Listen directly on your computer or on your mobile devices. If you have an android device you can follow my guide at Android Relish on Podax Podcasting & gPodder. In the guide it mentions the gPodder.net service and Podcast Directory, the desktop and mobile version can both be synced with the free gPodder.net service. The website has been unreachable once but aside from that there isn't a better place to discover and manage good podcasts.
gPodder is available for Linux, FreeBSD, Windows, Mac OS X and mobile devices like the Nokia N810, N900 and N9. Some of the highlights are that it has support for RSS, Atom, YouTube, Soundcloud, Vimeo and XSPF feeds, as well as exporting to OPML which can then be imported on an Android device. Easily synchronize between devices with full gpodder.net API support. gPodder is also easy customization with its' choice of supporting Python as it's extension language.
Source Code: http://gpodder.org/wiki/Git
Tutorial for using the gPodder.net for syncing multiple devices.
Heard about Concrete5 in a podcast from twit.tv called Floss Weekly [ FLOSS Weekly 239 ]. Am currently using Podax on Android to retrieve and listen to my podcasts and gPodder on my desktop to manage the shows I want. That's a hole other topic though so let's get back to how awesome Concrete5 is, and how they have successfully utilized Open Source and Creative Commons as the basis for their business model.
Concrete5 is a content management system that is free and open source, made for marketing but built for geeks. Concrete5 was designed for ease of use, for users with minimum technical skill can still make beautiful pages. It enables users to edit site content directly from the page. It provides version management for every page, similar to wiki software, so any edits can be viewed and reverted back to, also allows users to edit images through an embedded editor on the page.