Your computer works reasonably well but it runs slowly all the time. It was quite a lot faster in the past but it now takes a long time to start up, shut down or get anything done.
Slow PCs can be caused by several things. Make sure all your drivers are up to date (check the hardware makers’ websites), and see www.windowsupdate.com for the latest Windows patches.
If you installed any software just prior to your PC slowing down, try uninstalling it to see if that cures the problem.
Make sure that the computer’s hard disk is not full. Windows uses parts of the hard disk heavily in daily use for Virtual Memory, so you should have a large part (at least 1Gb, if the drive is larger than 10Gb) free for its use. To change Virtual Memory, right-click on My Computer, select Properties and then click on the Advanced tab. Click on Settings in the Performance box, select the Advanced tab and click on the Change button and then check, and change if required, the settings. Also, try defragmenting the hard disk with the tool built in to Windows. Click on Start, then on All Programs, Accessories, System Tools and finally Disk Defragmenter.