Man of Honour
Shouldn't make any difference today if the Lappy had a 7.2K HDD as it will be SATA 150 or SATA 300 anyhow.
I don't think interface speed is a limiting factor yet on normal mechanical drives... laptop (2.5") drives just are slower... even the modern ones I believe fall a long way behind their desktop relatives.
Interface speed does not mean drive speed. For example, a modern 2.5" mechanical drive with a ATA133 PATA interface will only be limited by the actual drive. (though a fast iface would be good for a drive with large cache I guess)
AFAIK only the new SSD on laptops are pushing iface speeds...and thats a guess as I don't find hardware that interesting any more