I second MalwareBytes, extremely useful tool.
Here are some programs that are easy to use, and might help:
CCleaner:
http://www.piriform.com/ccleaner- Helps cleans your hard drive, removes old temp files, etc. Easy to use and install.
If you have Windows 7, check and make sure you have it set to automatically defrag.
http://www.howtogeek.com/howto/windo...windows-vista/
Another thing to consider is heat. As your laptop gets older, it collects dust and can't get rid of heat like it used to. Checking for heat with a program like Core Temp:
http://www.alcpu.com/CoreTemp/ is useful to see if you need to buy an external laptop cooler. If the temperature is spiking into the 85-90C range, go ahead and buy a cooler.
That's probably a good start for now.