You will notice a speed bump for all disk related tasks, such as booting up. Given the fact that many people have complained about the vibrations and/or noise coming from 7200 rpm drives should be enough to you pause and consider the 5400.
The power consumption of 7200 drives is nearly identical to 5400 and the heat generation is the same, so the bottom line comes down to possible vibrations and cost.
For the record, I have a seagate 7200.4 500gig drive and I've not experienced any increase in vibrations or noise.