I just downloaded and installed CS 5.5. During the install, it said that I needed a bagillion more bytes of space left on my D: drive. But I told it to ignore the error and it installed.
Thanks for the report. I suspect you have an extra large drive on your system and the CodeSite 5 Installer is based on the old Wise Installation System tool, which is still quite good, but it does have issues with reporting the correct requirements on newer very large drives.