it sounds correct and it did "see" the scanner so there must be some other problem.
mine plugs into the tower also.

generally it doesn't matter much what brand the computer or scanner is.

the settings could be set wrong in the printer /scanner section of control panel.

I have 1 printer/ 1 printer/scanner/fax and a scanner so depending on which i might want to use as default - the correct one has to be set as default.

what is the Operating system ? Windows XP, Windows 2000 or older?