If you just got it in April, you probably have atleast two ports. Look in the front of the puter and see if you have a port there. If not, you should have two (atleast) right by the keyboard/mouse ports in the back. The USB port will look like this:
I just ordered a Sony DRU-500A. It does both formats (+R and -R). They also make an external version called DRX500UL. This one does Firewire and USB connections. If you want specs, you can look up DRX500UL on SonyStyle.com. I tried to link, but Sony's website hates us all.