Replying to Another Hard drive thread

Looking for a portable hard drive for all the footage of this year. Working with AVCHD, so Im thinking I  would prefer a larger drive (320/500.) I also want firewire 800, so far I have found two that look tempting, the Lacie 320gb rugged @ $130 and WD passport studio (320gb @ $120 & 500gb @ $150)
The difference between the two, the WD isnt rated to any drop and spindle speed is 5400 rpm. The Lacie is rated, and has a speed of 7200 rpm.

Now my questions are am I overlooking any other options (cheaper) and will the difference in spindle speed affect the performance?