By Brian O’Connell
The new weekly mortgage numbers are out and interest rates continue to flirt with the 5% level-and-under that borrowers have seen in recent weeks.

Rates for 30-year fixed mortgages are at 4.99%; compared to 5.04% last week; whole 15-year fixed rate mortgage rates are down to 4.76%, from 4.81% last week.

Sliding mortgage rates continue to fuel the current refinancing boomlet, as Fannie Mae (Stock Quote: FNM) reports that demand for home refinancing deals is at a six-year high, with volume at $77 billion for March 2009.

According to Fannie Mae, that’s twice the volume for February 2009, and five times the volume compared to January 2009.

Fannie Mae officials credit the government’s Making Homes Affordable Plan for helping trigger the refinancing stampede, with 500,000 U.S. borrowers contacting Fannie Mae’s web site to ask about refinancing.

With interest in refinancing at a six-year high, and declining home prices leading to some good home purchase deals, can home borrowers expect interest rates to remain below 5%? As usual, economic events have impacted rates, most notably last week after the Federal Accounting Standards Board announced that it would relax “mark to market” corporate accounting policies.

That, and the fact that the G-20 summit led to a global commitment to pour another $1 trillion into fighting the global economic downturn, fired up Wall Street, leading many investors to abandon safe haven investments and join the thundering herd back into stocks. As a result, mortgage rates were pushed slightly higher during the week and borrowing costs bounced upward, too.

Still, lenders are reporting that borrowers with good credit (a 740-point credit score or higher), who can document income and who are willing to pay all closing costs, can score interest rate deals in the 4.625%-and-4.875% levels for 30-year fixed mortgages.

To find out what kind of house a sub-5% mortgage rate will get you, check out the BankingMyway.com mortgage calculator.

—For more ways to save, spend, invest and borrow, visit MainStreet.com.