Is it possible to hold both H1 & B1 visas together

[roma4k]

Hi All,

I am in a situation, for which i seek your expert advise.

Case History:-
a)I was holding a H1B visa from Jan,2004 to Jan,2007 from Company A.
In Jan,2007, i got H1B renewed from Company B for another 3 years.

b)I have the renewed petition but still haven't got the H1B visa stamped again.

c)I am still working with Company A and now Company A wants me to get a B1 visa stamped.

Concerns:-
1)Is it possible to hold both H1B and B1 visas.
2)If i go for B1 stamping, will it have any effect on my H-1 visa.
At the time of B1 stamping, the US Immigration officials will see that i have a approved H1 visa petition
allthough the H1 visa has not been stamped.
In this case, will they cancel the B-1 visa stamping or the H-1 visa petetion ?
3)If i get the B1 visa stamped and then go for my H1 visa stamping, can i get the H1 visa stamped?
4)If i am able to get both B1 and H1 stamped and when i arrive in US, which visa shall i be allowed to enter US
Does this depend upon what kind of letter i am holding?

Kindly advise as i got not want any effects on the H1.

Waiting for an early reply.

Thanks & Regards,
Roma4k