Safely connecting external drive to laptop

Just use the USB 2.0 cable.  You don't have Firewire 800 in the notebook and the difference between firewire 400 and USB 2.0 in the real world is nil.

I just got an external enclosure to house an internal drive to connect to my Inspiron 9300.  The enclosure is very good and came with cables for connecting to its USB2.0, firewire 400, firewire 800, and eSATA ports.  The problem is that I can only physically connect the USB 2.0 cable to my laptop.  There is a port that says 1394 on the right side of the laptop but the firewire cable does not fit into it.  My question is would it be safe to buy some kind of adaptor device to attach to one end of the cable so I could plug it into one of the USB slots in my computer (the square looking slots on the side and back)?  I read somewhere that someone tried this with a firewire 400 or 800 cable and it burned out the internal drive of his computer because the voltages were different.  Would something like this work?  The reason I am interested is because I heard that firewire 400 and 800 are faster than USB 2.0.