http://pixologic.com/zbrush/downloadcenter/alpha/
should be fine.
Texures.com has been playing some students up with not giving the free credits. It is unclear if this is deliberate policy change as some of those students e-mail them an say they then get them.
It is also possible to search for such resources on the web, or look through the wiki page here of suggested texture and other sites. WIKI - Free Blender Resources