There are a couple of ways we can look at this, so I'll draft up two charts for you.

For the first one, I'm basing it on a 30 year term, a 6.5% rate to start (last average rate I saw on mortgage news daily's website) and then the savings on dropping it down to a 5.5% at the same 30 year with the lower interest rate and the lower payment.

This is the full savings over 30 years, if you never refinance, modify, or pay off the mortgage early.

part one: today's rates minus 1%

Balance	Savings
$800,000	$185,124
$775,000	$179,338
$750,000	$173,553
$725,000	$167,768
$700,000	$161,983
$675,000	$156,198
$650,000	$150,413
$625,000	$144,628
$600,000	$138,843
$575,000	$133,058
$550,000	$127,272
$525,000	$121,487
$500,000	$115,702
$475,000	$109,917
$450,000	$104,132
$425,000	$98,347
$400,000	$92,562
$375,000	$86,777
$350,000	$80,992
$325,000	$75,206
$300,000	$69,421
$275,000	$63,636
$250,000	$57,851
$225,000	$52,066
$200,000	$46,281
$175,000	$40,496
$150,000	$34,711
$125,000	$28,926
$100,000	$23,140

part two: today's median home price

If I take 95% (5% down payment) of today's $443,471 median home price, then I have a $421,297.45 loan amount. Let's see what a 1% decrease of 30 years of interest does to that balance.

From	To	Savings
8%	7%	$103,834
7.875%	6.875%	$103,347
7.75%	6.75%	$102,852
7.625%	6.625%	$102,349
7.5%	6.5%	$101,839
7.375%	6.375%	$101,322
7.25%	6.25%	$100.797
7.125%	6.125%	$100,264
7%	6%	$99,724
6.875%	5.875%	$99,177
6.75%	5.75%	$98,622
6.625%	5.625%	$98,060
6.5%	5.5%	$97,490
6.375%	5.375%	$97,913
6.25%	5.25%	$96,329
6.125%	5.125%	$96,738
6%	5%	$95,139
5.875%	4.875%	$94,533
5.75%	4.75%	$93,921
5.625%	4.625%	$93,301
5.5%	4.5%	$92,674
5.375%	4.375%	$92,041
5.25%	4.25%	$91,400
5.125%	4.125%	$90,753
5%	4%	$90,100
4.875%	3.875%	$89,440
4.75%	3.75%	$88,773
4.625%	3.625%	$88,101
4.5%	3.5%	$87,422
4.375%	3.375%	$86,737
4.25%	3.25%	$86,046
4.125%	3.125%	$85,350
4%	3%	$84,647
3.875%	2.875%	$83,940
3.75%	2.75%	$83,226
3.625%	2.625%	$82,508
3.5%	2.5%	$81,785
3.375%	2.375%	$81,056
3.25%	2.25%	$80,323
3.125%	2.125%	$79,586
3%	2%	$78,843
2.875%	1.875%	$78,097
2.75%	1.75%	$77,347
2.625%	1.625%	$76,593
2.5%	1.5%	$75,835
2.375%	1.375%	$75,073
2.25%	1.25%	$74,308
2.125%	1.125%	$73,541
2%	1%	$72,770