Steam gives me the error, "Steam requires that ~/Library/Application Support/Steam be created on a case insensitive filesystem." or "Steam requires that ~/Documents/Steam Content be created on a case insensitive filesystem."
Steam does not currently support case sensitive filesystems or partitions.
If you wish to use Steam please make sure of the following:
To check whether you have a case-sensitive partition:
"Case-sensitive Journaled HFS" (hard drive IS case-sensitive), or "Journaled HFS" (hard drive is NOT case-sensitive)
For advanced users familiar with Unix and Terminal that wish to use symbolic links to get your case-sensitive system to work, you can refer to the following thread here.
Otherwise, you will need to install Steam to a different partition on this computer, or a different harddrive completely.