I've never had ANY luck with programs that are supposed to speed up a PC. The best way to speed up a PC other than upgrading hardware, is to do a FULL factory restore or format and reinstall windows. This will wipe the computer clean and give a fresh start. You'd have to backup all files first, and I am aware that doing all this can be a huge hassle, but is the best way to speed it up by far.
If wiping the PC isn't an option, doing a proper computer maintenance is in order. Also, there are some tricks you can do to speed up a PC, such as disable visual effects, increase virtual memory (page file), turn a USB flash stick into RAM by using the Windows "ReadyBoost" feature.
The two programs I do recommend you have are Ccleaner and Malwarebytes. Run a full scan with malwarebytes to ensure you don't have any malware, spyware, adware, or viruses slowing down your system.
Ccleaner has many features and its important to properly learn how to use ALL of them. The main feature is the "Run Cleaner" option which cleans up all the junk and unneeded files on your PC. It also has a registry cleaner I suggest you use, but most importantly, CCleaner has an option under "Tools" that allows you to select which start up programs and services should be starting up when your computer boots into Windows. This is one of the best and most important things you can do to speed up your computer. Most people will have dozens of programs and services running in the background that they didn't even know about. Most of these programs and services shouldn't be running at all times. Stopping the services or startup programs does NOT uninstall the program, although I also recommend you uninstall all programs on your computer you don't use or don't need.
You should also be defraging the hard drive often. Windows Vista, and Windows 7 are set to defrag automatically once a week, but its important to make sure the program IS running correctly and on schedule.
The other two computer maintenance commands you should be using that are run from the windows command prompt are: chkdsk (if it finds errors, then schedule a boot time chkdsk with the command: chkdsk /r ) You should also read about the sfc /scannow command which will scan all windows system files for errors and repair. (Note: for windows 7 and vista, you'll have to RIGHT click on the command prompt and select "Run as Administrator", in order to run the command)
Also what are you using for Anti Virus? Some antivirus programs are very high on system resources and can really slow down your PC. For a very fast antivirus solution, try Panda Cloud Antivirus (fastest antivirus software by far) or Microsoft Security Essentials.
Please read my guide on "How to Speed Up Your PC and Keep it Happy". http://www.eugenecomputergeeks.com/Guide-how-to-speed-up-your-PC-and-keep-it-happy.html The guide has everything you could possibly need to know about speeding up a computer.
Hopefully I helped a bit with speeding up your PC. If you have any other questions, please don't hesitate to ask. Thanks