Many people know you should have the Adobe Reader to read PDF files. Maybe it was pre-installed on your PC. If it is old you can visit that web site to get a new version.
One of the difficult transitional issues is MS Office 2003 vs 2007. If you have an older version of MS Office you may not be able to read files created in the newer version. This is why I recommend that you save files in the previous MS Office 97-2003 format. But you don't necessarily have control of what file format you receive. And if you receive a 2007 file from a perspective employer it may be embarrassing to tell them you can't read it (not even at the resource centers).
If you have MS Office XP or 2003 you can update your product to be able to understand the 2007 formats by following the directions here. A less intrusive solution is to install the MS Office viewers - Word, Excel, Powerpoint.
These viewers are very large and can not be efficiently downloaded over dialup. If you don't have a high speed link then goto a resource center or library, download these to a flash drive and then install them on your home PC.
Another thing you may want to do is a search on each viewer to see if their are functional or security updates for any of them. You can do this search from the top of the pages I have linked above. The very top search box is for the web, use the second search box under the heading "Download Center" after the "Search All Downloads" box. Click on release date to sort, new security fixes won't be high on the default popularity post.
Side note: I got this post idea from a page at the Ohio LMI site, but before I posted it, I saw that two of the links were backlevel to 2003, so I looked up the newer file viewers.