There are perhaps 12 different free
PR distribution systems. It is probably worth putting your news release out on all of them if you have time. Two of them will automatically get included in google News search, which is a bonus.
The other advantage is that you will have incoming extra links to your site.
However, no free system is going to actively send your press release round to newsppaper and magazine editors unless you actually pay. If your site is specirfically newsworthy - and a current news item is much better than just a general mention of your site, then do consider paying real money.
If your site is within a specirfic subject area, suggest you also take time to seek out publications who publish news about this, find email addresses of editors, and maybe use something like Mach5 Mailer to send your own news release emails directly to these editors from time to time.
Do take time though to learn how best to write a compelling newsworthy press release - there are a number of online guides.
Best wishes
Tony