TD2-7 first round question

[MarkGritter]

The more I play TD the less I understand it.

Say you're in the big blind at the Stars $5/$10 game. UTG raises, the SB makes it three bets, and you have 8643x. Both players already in the pot are regulars with more or less solid play.

Call, cap, or fold? Why?

If one of the players is pat, how far do you continue with the hand?

Would holding 8642 instead make any difference?