YEP it is a very large file 178.5Mb. Try this link from within your browser (I use Firefox as it has the better resume function) https://swdlp.apple.com/cgi-bin/WebO...rp_code=itunes then just let your browser download run overnight.
If you have problems with the download stalling etc, try these remedies How do you resume an interrupted download in Apple Safari & Firefox you will notice that Firefox has the better resume function than Safari.
As for iOS5.1.1 here are some direct links: iOS 5.1.1 Released [Direct Download Links] you will need to download a separate file for each iDevice and model.
Cambodia is a wonderful lovely country. We did the boat cruise from Saigon to Siem Reap in 2010. Then did the Temples at Angkor.