If you want to keep your computer “portable”, then replace the drive with either 7590S or 7700S (maybe 7590S better, but 7700 newer…other slim drive are AFAIK a waste of money).
If you want reliable, fast and easy burning and reading, you’d better go for an external usb or usb/esata enclosure like Vantec NST530U, and a cheap and good sata drive like Optiarc AD-7240S (or 7241 with sata, 7243 labelflash).
With this enclosure (530U) and 7240S, I’m able to reach 22x while burning (power supply is a little weak for 24x) with esata, and 16x with usb. For me, it’s the way to go if you want reliable and efficient burning.
External slim drive are perhaps handy, but they violate usb specification most of the time (until usb3 will be widespread), and they won’t burn better than internal slim Optiarc (in ide, you also have Pioneer slim drive that are quite good), except if you buy the Sony one, that is a 7590 internally.