that is same like AT89C51 ok?
if u have any idea of AT89C51, AT89S51 is same.
only some following diffrences r there.
AT89S51 has more speed (upto 33MHz)
it has builtin watchdog.
its programmer is so simple.
toherwise every thing is same to AT89C51.
AT89S51/52 is greap MCU )) I'm using it in some projects.
Read the data sheet from Atmel, and the book for 8051 which you prefer and have ))
You can use keil c51, franklin and etc tools...
Programming algo is easy... U can make a programmer and You can buy if don't like to lose your time