Currently I am working for Company A and they are planning to process my L1 visa.
But in Oct, 2006 I got my H1 petition approved from Company B, which is valid till Oct, 2009. I am yet to go for H1 visa stamping.

Initially I prefer to go to US on L1 visa (because my wife can also work on EAD) and then later change to Company B on H1.

What is the best way that I can do ?

1) After going to US on L1 visa, can I change to company B on H1? To do this shall I get my H1 visa also stamped in India?
2) or shall I go to US without H1 stamping and then apply for COS from L1 to H1? Is it possible to do COS for H1 that is approved before L1?

I currently hold a 10 year B1 visa also.

Please give your advice.