Like the car in the backyard your PC needs maintenance. This isn't a complex job, and it costs nothing. You can find Ccleaner(the tool you will use first to clean your temporary files and registry, and to set the programs that will start automaticly at startup) here! Also, after you have finished cleaning your PC you will want to use the Defraggler(which defragments your computer), or you can use the windows defragmenter(I prefer Deraggler). Click here to go to Defraggler homepage. Both Defraggler and Ccleaner are made by Piriform. Click here to go to Piriform home. Also, there is the virus issue. But, taking in consideration how many virus scanners are out there, I will let you decide which one suits you.
Open Office org
Open Office org is very similar to Microsoft Office, but it's made by Sun Microsystems. Also, it has great advantages, for example your data is stored in an international open standard format. Open Office.org 3 is the result of over twenty years' software engineering. Designed from the start as a single piece of software it has a consistency other products cannot match. A completely open development process means that anyone can report bugs, request new features, or enhance the software. You can download Open Office.org here. Below are a couple of screenshots.