If you are new to writing code for the 8051 using C, then the following may be of help. I found it good.

Book : Embedded C by Michael J. Pont. Available from Amazom.com

I also have the PDF of the course material that is used to teach this topic, by the same author. It has references to the above mentioned book. Unfortunatley I do not remember where I downloaded it from. So the only way is to mail it to you if you want it - it is free for circulation as long as you dont modify it. Send me a mail if you do want it.

Raghu