Microsoft Office 2007 comes in several different suites with offerings ranging from basic to enterprise. This makes it easier for individuals and businesses to select the best suite for their needs without having to pay for applications that they don't want. For example, I also have Microsoft Office on my computer and, just like you, I don't have Access. In my case, I need Microsoft Word and Excel but I don't need Outlook, Access, Publisher, and the other products.
The applications found in the Microsoft Office 2007 lineup include: Access 2007, Communicator 2007, Excel 2007, Groove 2007, InfoPath 2007, OneNote 2007, Accounting Express 2008 (in US and UK markets only), Outlook 2007, Outlook 2007 with Business Contact Manager, PowerPoint 2007, Publisher 2007, and Word 2007.
Microsoft Office suites include: Microsoft Office Basic 2007, Microsoft Office Standard 2007, Microsoft Office Home and Student 2007, Microsoft Office Small Business 2007, Microsoft Office Professional, Microsoft Office Professional Plus, and Microsoft Office Enterprise 2007.
Each suite bundles a different combination of applications which gives users the ability to purchase the suite that best meets their needs. I chose the Home and Student 2007 edition because it came with both Microsoft Word and Excel. It also came with PowerPoint as well as OneNote -both applications that I didn't necessarily want but didn't object to either.
While I do like Microsoft Access, it's not a program that I need. To me, it wasn't worth the price of jumping up to the Microsoft Office Professional 2007 suite just to get that one additional application. The Home and Student version cost me about $150 while jumping up to Microsoft Office Professional would have cost me $500. If I ever find that I really need Access, I can purchase it separately for about $230. Yes, it's more expensive to buy Access ala carte but in my case, I'd still be money ahead. Depending on the version of Microsoft Office that you purchased, you may be money ahead too.