contract assignement - can i leave?

[mlpathir]

hi,

a consulting firm holds my h1b and i am working with a end client through a tier-1 vendor. there is a po b/w my firm and vendor for 4+ months.

now i got a permanent employment opprotunity with a big company who are ready to transfer my h1b

questions:

1. can i break the po and leave the client place with or without notice period?
2. is there any risk if my firm came to know about this?
3. any probable risks in doing this and better way of overcoming them?

pls advice asap