Hi AthaNz,
you can use "show int port-util" on the 5400 to show per interface load. On specific interfaces, a "sh int <interface>" will also show the load for that interface.
By the way to all the Aruba CX switch gurus out there: Is there an equivalent to "sh int port-util" on CX?? If not i would definitely recommend this being incorporated in one of the upcoming releases.
Cheers Frank.