More than likely, your installation formatted the disk, and probably removed any viruses that were there. Was this previously a Windows system?
As to your boot up, what does "only that hard drive shows up" mean?
You might have a video problem, and that would require booting into recovery; running dpkg-reconfigure xserver-xorg; taking all default answers; except for resolution, where you might choose some lower settings. It could be the video driver; or you could have a botched install.
Try to look at the installation logs under /var/log. I have forgotten the names of those logs, but they may have install or dpkg in the log file name.
If all else fails, post the logs up on Ubuntu Launchpad --
-- along with an installation bug report.