Vista has become very sluggish

I have Win Vista Business installed on a Lenovo Thinkpad (2.2 GHz, 3GB RAM,
43% of Hard Disk used) which has become very sluggish of late; keystrokes
often take a long time to register, tabbing between windows is slow and
sometimes does not work at all, not as many windows can be opened at the
same time as in the past and so on.

I have done a virus and malware check (Avast AV & AdAware are resident),
defragged the hard disk and also done a Windows memory check, none of which
found any problems.

Does anyone know what could be the problem and how it could be resolved?

Thanks

See whether these Tutorials help you
http://www.vistax64.com/tutorials/81...ta.html?filter[11]=Performanc
Maintenanc
http://www.vistax64.com/tutorials/16...er.html?filter[11]=Performanc
Maintenanc

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brummyfa