If Obama is disqualified then his EC votes are either disqualified along with him (constitutional path), or they go to Biden (voter intent BS path). If Biden doesn't get them (or enough of them) then McCain should win the EC vote. If for some reason nobody gets a majority of the EC votes cast then the election goes to the House. The House then votes at one vote per state. The states are constrained to choosing one of the top three candidates (Obama (who is disqualified), McCain, Nader, or, arguably, one of the top three qualified candidates, McCain, Nader and Barr) by a simple majority of all the States (26) with a quorum of 2/3 of the States (34). [12th Amendment] The same process applies to the VP, so Biden will end up VP in the EC even if he ends up President later on. Note that the 12th Amendment specifically separates the EC and House voting process for President from that for VP, so Biden cannot be selected President by this process.
If, after the EC convenes, it is determined that Obama was not qualified, then he won't be able to take office and the VP (Biden) becomes Acting President until the President can resume his duties (never) or is removed from office (again, never, since he cannot take office in the first place. It has been suggested that a President-elect can be impeached but I have no evidence to support that). [25th Amendment] So, in this scenario, Biden is Acting President for four years.
If, after the Inauguration it is determined that Obama was not qualified, he would be impeached, and Biden becomes President. If Biden is implicated in the deception about Obama's Constitutional qualifications, then he, too, would be impeached and then Pelosi ends up President. After her then President pro tempore of the Senate, then the Secretary of State, etc.
How about this for a wacky scenario: After the EC convenes but before the Inauguration, Obama is disqualified and Impeached and Biden, Pelosi (Speaker) and Byrd (current President pro tempore of the Senate) are all implicated in the coverup and removed from office. Who ends up President? Condoleezza Rice. Since the new President and cabinet never took office, the existing Secretary of State is next in the line of succession. Far fetched, but possible.
“VP (Biden) becomes Acting President”
and the 20th Amendment, of course.
What if they somehow confirm Hillary as SoS in early January in the middle of all that?!
Maybe Acting President Biden would spend his entire term demanding the Obamabot zombie army push thru a Constitutional amendment or con-con to push Obama into office. Could get ugly.