Click Start
Click Run
Enter MSCONFIG
Click OK
Remove (uncheck) everything from the Startup list unless it's obvious that you need it - security stuff etc.
My machine has just the first four boxes checked.
Get hold of Spybot Search & Destroy (free) and run it
Get hold of Piriform's CCleaner (free) and use it to clean up your machines registry
Defrag the disk(s)
Right click in the Taskbar (at the bottom of the screen)
and select task manager Select the Processes Tab and look at the CPU column - be suspicious of anything of unknown origin that appears to be eating the CPU time - consider deleting it using add/delete programs.
If none of this works investigate the memory situation - many people say more memory helps but I'm not convinced that it always does - computers often get infected with all kinds of unwanted crud which you never asked for and are often unaware of - bit by bit they get slower and slower.
Peccavi
March 2009