also
download
speedfan
and post your temps as your multitasking. Make sure your box/fans are clean.
what are your power supply specs?
When was the last time you reapplied artic 5?
instructions
Lastly list your infection protection, is norton installed?
And a 5 gig partition for windows is borderline, I know there are opinions of the nature that the seek performance is better with a small partition, but...