GC while expecting to study - Urgent

[readerregular]

Hi,
I have been unable to post at the forum and don't seem to be able to find an answer. Can you help me with this question?
My company wants to start my GC processing under EB1 category. I want to pursue graduate studies by Fall 2009 for which I apply in a few months. If I get a seat for that year, I will have my I-20 by January 2009.
What will be the effect of my case if I cancel my GC processing and instead go for F1 processing?
Or can i continue with my graduate course if I have passed the I - 485 phase and yet not received my GC?
Or, will I have to give up my I-20 and instead wait for my GC processing to complete?

My doubts arise because I clearly dont understand the impact of one on the other.
You guidance will be appreciated with sincerity.
Regards

[txh1b]

COS to F1 after filing I485 may not be possible and a visa stamping for F1 after filing 485 is almost impossible. You can continue your studies as a parolee without changing to F1 status maintaining your current job on EAD or your student assistantship on EAD.