I tried installing using Wubi. It is stuck at the "1 hr remaining"-message for several hours. The same has happened in previous 4-6 installation attempt. What could be the problem?
This question was answered in a comment. (While the situation here may have been temporary, it's the sort of thing that recurs, so I believe this is valuable as an answer.)
Probably the servers are overloaded. Try downloading the ISO yourself using a bittorrent client and save it in the same directory as wubi.exe before running. Or try again later.