When i was in B.Sc. one of my friend suggested me a project that was with a PIC microcontroller, later i explored a no of nice projects with microcontroller. So i started googling on the word.
after 2 year in M.Sc. i choosed my special paper embedded systems that helped me a lot. Bcoz that led me to a workshop on AVR.
AVR: i had started with ATMega8L (Make:Atmel, Arch:AVR) , i suggest you to start with AVR because it supports STK200(cheap), Codevision AVR C Compiler( Easiest) although the chip costs a bit higher(5 times that of 8051). The overall cost is lower than other microcontrollers.
PIC: PIC also supports easy programmers with a no of components.