You mean upgrade the existing 5400RPM drives to 7200RPM? It is normally possible to do so on a laptop but it requires:
- 7200RPM drives of the same dimensions as the old ones (exactly, so it pretty much implies that they must be the same since the original ones are identical)
- opening up your laptop and unscrewing the hard drives to replace them
Remember to safely backup your data before attempting anything, and take extra care with backing up the operating system.
I'm not sure if HP has this but many laptop retailers offer the service to upgrade their laptops' hard drives themselves, for a little fee. You could perhaps look into this, it would be hassle free and much easier. If HP doesn't, then most electronics shops do it as well, so if there's one near your place it may be the best option.
Nice laptop by the way. If you need any further information feel free to ask.