Much of the C code for a different processor would work on a PIC. However, there is the initialization of the PIC hardware that would be different and you would need to write. You would also need to buy a device to program the hex file into the PIC. The PICKit2 from Microchip is highly recommended and only costs $35.
A nice feature of the Microchip tools, MPLAB and HiTech C compiler, is that they are free to download. You can then start learning and working on code without buying anything. Since you already have experience with PICs and MPLAB go for it. The AVR source code for the $50 bot is also free so you can work on porting it to a PIC.
Good luck and have fun.