When I was using my Mac Book Pro, I used iTunes to play all of my content. iTunes makes it easy to organize your audio collection as well as play your subscribed podcasts. Obvousily, iTunes will synchronize content with iPods.
When I switched to Ubuntu, I looked for a music player that would have a similar feature set. I heard about Amarok, but I couldn't figure out how to import the OPML feed from iTunes. Also I couldn't find a menu to subcribe to a podcast feed url.
I started to use gPodder, as I was able to import my OPML file, if I posted it to a web accessible place. gPodder uses Movie Player to actually play the content. This is great as it can play many formats. Unfortunately, this also means the gPodder can not track podcast play state to know when to delete the file. Also it doesn't rememer the play position if you pause while playing a partictular eposide.
I took another look at Amarok, and then I relaized that there were a bunch of tabs along the left side. The "Playlist" tab has a "Podcasts" folder. If you right click on that folder, you can add a podcast feed. I have added both my audio and video feeds to Amarok. I listen to the audio podcasts within Amarok, and have configured Amarok to launch Movie Player for video items.