DSP recommendation for beginners
The dsPIC30F line of microcontrollers from Microchip are excellent introductory DSPs.  They are programmed in C or assembly in the same way that other PICs are, but include DSP libraries that help with filtering, etc.  They have all the necessary peripherals for most projects (ADC, DAC, serial communications, timers, the list goes on and on). They are fairly cheap (no more than $10), can be sampled in through-hole packaging, and can be programmed with standard PIC programmers and debuggers.