waiting fro I140 approval

[waitin]

I have recd my labor approval and I aplied for I 140 in NOv 2006. REcd the letter. Now my wife and kids are planning to go to India nad their Visa as of now has expired but we have renewed it here and got new I 94 . Now if they are going they will be able to come back without trouble or they have to go to embassy agaain to get visa?? will that be difficult . I have to send pay stubs and hb1 approved petition>>??any thing else . My wife and kids are with me for over 3 years.. What needs to be done. Will there be any problem??
Pleeees reply.......fast


Thanks....