If you own a Windows computer, listen carefully. Microsoft is finally making Office 2013 widely available to the masses today. This release is radically different from previous versions of Office, as Microsoft is offering the software pack in subscription form, named Office 365 Home Premium. This subscription charges users a monthly or annual “rental” fee and gives you the right to install Office 2013 or Office For Mac 2011 on up to five computers. Microsoft will also offer traditional single-user installs of their different packages – like Home and Student or Home and Business – though as of last night they had yet to unveil exact pricing. Industry experts believe it to be about $139 for the Home and Student and $219 for Home and Business per installation. This week also marks the final chance to purchase a Windows 8 upgrade for its ultra-low cost of $39. Beginning on Friday, February 1, the price jumps to its full cost: $119 for the regular edition and $199 for Pro.