What software and hosting do I need to start an online community site where people can post articles or music?

I’d like to start an online site like ezinearticles or other article posting site. What host and/or what software is required?
Also, I’d like to start an online site for musicians to post their songs and blogs.
What hosts do you recommend and what software or program for these? Thanks.
To clarify – I want to open a large site 1 – offering members a free webpage and the ability to submit many articles each, photos, and comments, etc., like ezinearticles.com or those others.

Also, for another site, 2 – I’d like to open a music site, where music artists can upload their own songs, videos and info, blogs,etc. sell music maybe, promote, add photos, and so on.

I’d like for each site to have all the modern features – is this a joomla site, I’m wondering? (Post nuke wouldn’t work for this, I’m told and not a wiki either, but I’d like to use an open source or a cheap,but reliable way to do this.)

Usually a host or server must be pretty large, depending upon the numbers. Upgrades are, of course, inevitable though.

Will I need a server of my own? Will I be able just to pay the host, get a software program, download one, like joomla or what ?
Any info on this? Thanks.
None of the hosting places suggested so far do anything of this kind.

Does Joomla ?
Does anyone know of any program, platform, or hosting place where I can go to start sites likes this?
Thanks again.