Office 2003 updates expire in April 2014 which will leave it vulnerable to attacks. There are several options for upgrading from Office 2003.
The cheapest option is to rent Office 365 Home Premium. It costs $9.99/month or $99.99/year.
The Office 365 Business costs more but it includes a SharePoint website. It costs $5-$15/month per user.
If you need Office 2013 on multiple PCs then it’s cheaper to get a subscription. If you need the Professional version on multiple PCs then a subscription is a no-brainer.
Note that Windows Vista users, will have to opt for Office 2010. Office 2013 is not supported for Vista.
Renting Office 365 Home Premium
Upgrading to Office 2013 365 is very simple. You can get started with a trial subscription . You get access to the Professional Suite plus 20G OneDrive and 60 minutes of free Skype phone calls/month. You also get free upgrades and best of all you can use the software on 5 PCs or Macs. The down side is that you don’t get a permanent license.
Buying Office 2013
You can buy Office 2013 but the Professional version can be expensive. You can get Office Home & Student 2013 for $139.99 from Microsoft but it doesn’t include Outlook. If you want Outlook it will cost you $219.99. If you need Publisher or Access you need the Professional version which costs $399.99.
You can find cheaper prices with a Google search. Nextag shows the Professional version for as cheap as $164 but then you need to investigate the seller’s reputation.
Buying Older Versions Office
You can also buy an older version of Office like Office 2010. If you don’t need the features of newer versions then you can get the older versions cheaper using Google & Nextag.
Again you will need to validate the reputation and legality of whomever you purchase from.
This route is mandatory for Windows Vista Users. Windows Vista has roughly 3% of the desktop operating systems.