Theres no way a gpu would bottleneck opening a word document...
Check to see if the drive is set to spin down after a set time.
Check to see if a cd or dvd drive is on the same IDE cable as the HDD. (if the HDD is ata) put each on its own cable if they are; follow the manufacturers spec for setting the master/slave/single jumper.
If the HDD is IDE/ATA then check to see if the drive has dropped out of DMA mode. You can google how to check this.
post back and update us :-)