Slow computer

[Mario]

my sisters computer is quite slow for some reason, all its hardware is better than in my computer and its still slow, ive run several virus scans and none have found anything, i defrag it regularly, it has loads of disk space left and i just cant think of any other ways to speed it up, in theory it should be faster than my computer but its twice as slow, can anyone recommend anything to try?

[N!ck]

Download and run this on it and post the results. http://www.trendsecure.com/portal/en-US/tools/security_tools/hijackthis/download

[Mario]

Download and run this on it and post the results. http://www.trendsecure.com/portal/en-US/tools/security_tools/hijackthis/download
i'll pm you the results when i get chance to go on it.