So, a few points:
The vast majority of QE has gone to purchase treasury securities, not MBSs.
Secondly, if you look at the non-treasury securities purchased, the government is intending to hold them to maturity, and let them expire. That is the relief they are giving the banks...the banks, needing liquidity, couldn't hold on to the bonds for 10-20-30+ years like the Federal Reserve can.
Thirdly, QE has some positive effects of re-balancing the portfolios of the private sector. Truly, it gives them some more liquidity. But the major downside is that banks no longer are earning interest on those bonds (both treasury bonds and otherwise).
The net affect is that QE will drain wealth from economy in the long-term. Banks have replaced interest-earning assets with non-interest earning assets.
Plan for eliminating the national debt in 10-20 years:
Specific cuts; defense spending: http://rolexian.wordpress.com/2011/01/03/more-detailed-look-a