a) Clear out all temporary files and folders -- use Crap Cleaner click here
It will be fine on its default setings
b) Scan for malware spyware and viruses --Free Anti Spyware :-
Superantispyware click here
Malware removal tool click here
Free Antivirus software
MicroSoft Security Essentials click here
Avast click here
AVG antivirus click here
c) Clean the registry -- Use the tool in Crap Cleaner its very safe and also allows you to back up the registry first.
d) Pagefile (Virtual Memory) -- Right click MY Computer - select properties - Advanced tab - Performance -
advanced tab - Virtual memory click change, you can put the page file on a different drive (if you have one), click custom size and set Initial size to one and a half times the amount of memory you have fitted i.e. 512MB memory = set to 768MB, set maximum to double your memory amount i.e. 512MB memory = 1024MB click ok.
If your hard drive is full and there is not enough room for the pagefile this can slow down, freeze or even cause the PC to crash (restart).
e) Cut down on the programs that load at start up -- Start - Run type msconfig - start up tab- untick everything
except for firewall, antivirus and antispyware
and the services that run in the background. click here