Try right-clicking My Computer and selecting Properties, then go to the Advanced tab and click the Settings button for Performance. Under the "Visual Effects" tab, change that from letting Windows do the choosing to: "Adjust for best Performance". (Do not click the Apply/OK buttons just yet.)
Then in that same dialog window, go to the "Advanced" tab. Is everything set to best performance for Programs?? It should be!!! (Now click the Apply/OK buttons.)
From the START toolbar, click RUN... and type in MSCONFIG and click OK. This will show you many things about your system, including what Tasks and Services that have been started. Not all of those are really needed and some can be "turned off".
From the START toolbar, click RUN... and type in REGEDIT and click OK. This will bring up the System Registry. There are two main places where programs/tasks can be started from, and some of those may be deleted when found there:
From the START toolbar, click RUN... and type in SYSEDIT and click OK. This will bring up the System Configuration Editor, which can have the following text files showing within it:
There could be Programs (and Drivers) set to start up and run automatically when the computer is booted up, but really do not need to be there. They could be just the program name (usually with the directory path), part of a RUN= statement, or part of a DEVICE= statement.
Add more RAM to your system, usually 2-GigaBytes per processor (min: 1-GB per proc).
Delete the following files, where the asterisk (*) is a wild-card character used during searches:
~*.* (the preceding tilde usually means a temporary file).
History and Cache files.
And some *.LOG files (only if not needed).
Defrag your hard-drive (after deleting all unwanted files). You should have at least 5-GB of free space available (min: 2.5-GB).