I don't know about loading pages, but I do know that people have all sorts of problems with the ENC28J60 shield.
If you do a forum search for Ethernet shield, and look at threads where people are having problems, I'd say that 9 times out of 10 they're using the ENC28J60.
The Wiznet is more documented, tested, and overall used which leads to a LOT of sample scripts for doing pretty much anything you could ever want to do! 
I can see the appeal of the cheaper ENC28J60 shield (in fact, I almost bought one the other day because I saw it cheap), but in reality, you only save about $5-10 USD (here's the ENC28j60 for $24.95, and here's the Wiznet for $29.00).
I recommend you just save up the extra few bucks and go with what we all know works well :).