hi,the quickest and eaisest way i've found is to use Partion Magic. The program is real simple to use and is even capable to keeping any data intact. You will need to buy it but i think its worth it
Hey,The only problem that i seem to have with MP4 players apart form their excessive price tags is that many of them dont support many codecs / file types as you may like. You can get ones cheaply but all the decent ones with decent supporting of multiple codecs cost heaps.