I'll try to answer your question. Hopefully i've understood the question right.
1) Firstly, in Office 2007 (which i'm using), I can open a single word document, a single excel document and a single powerpoint document side by side (am currently not using Access). So that is not the issue.
2) I think what you want to do is to open multiple word docs, multiple excel files etc. simultaneously.
Open Word 2007, click on "View" tab at the top, then click on "Arrange All". You'll now find that you can open multiple documents, they will all show up in the task bar.
Also, if in Word 2007, you click on Office Button, Word Options, Advanced, then scroll down to the "Display" group and uncheck the "Show all windows in the Taskbar" box, then click on OK, you 'll find that only one window shows in the taskbar but the different open files are all arranged side by side in that window.
Try repeating this process in Excel, Powerpoint etc.