Answers: PC - Windows (by Microsoft), for a Mac - Mac OS X
PC - Windows (by Microsoft) or Linux distributions
iMac/MacBook - Macintosh (by Apple)
:)
Dont reason nearby is one for both
Mac is callled MAC X and laptop is Windows
There are several from respectively.
Windows offer Windows 2000, XP, NT, CE, Me, Vista and more.
Mac offer the elder OS's thru 9.2 after shifts to
OX 10.1 thru 10.4.11 to the severely soon to be released 10.5.