Fernimal,
Sorry that you are seeing this issue. I see no issues accessing the update sites at my end. It might be a temporary glitch at your end either with internet connection or the firewall/proxy is blocking the sites.
The update sites are meant to be used from within the IDE. You cannot access them directly from the browser.
Please make sure you have unfettered access to these sites through your proxy : http://www.genuitec.com, http://www.poweredbypulse.com and http://www.myeclipseide.com,www.downloads.genuitec.com for http and https.
Also ensure that there are no glitches in your internet connection.
Let us know how it works for you.
–Swapna
MyEclipse Support