I'm currently using a variety of RSS readers, but I've not found one that does exactly what I want.

Essentially I'd like it to pull down articles/webcomics/podcasts and save the attached files. NetNewsWire on the Mac seems to do the closest to what I want (it automatically downloads enclosed files), but it still lacks good offline caching.

Most importantly I want a reader that will archive the images in posts. Some claim to archive posts as HTML, but they still only drag down the text, no images - I read a lot of photography blogs so this is a problem. I'd like a reader that will let me build up a collection of my favourite blogs/webcomics/feeds and save it all offline so it doesn't have to reload anything when I view older stuff.

Any suggetsions Mac/Win would be good! I don't mind if it works on one or t'other or both.

I also use Thunderbird for all my emails so ideally if there's a way to do it in that... but from what I've seen Thunderbird doesn't support automatic downloads of attachments like video/music blogs.