As mentioned above... Image the drive, then replace the HD with a Solid State Drive (restore the image so that everything you had is still there). You'll get a huge increase in the access times with respect to the drive. This will greatly improve performance. Note that your Sony uses a PATA interface, so you will need to get a PATA SSD (obviously...
)
As for the SDIO slot, unless you get a Class 6 or higher (and your laptop supports it), you won't get much in the way of an improvement.
OIC!