OK, I'm currently (by my estimates) about 20K-30K underwater with a 30Y fixed mortgage @ %5.75 and an interest only HELOC @ %7.63.

You've got a lot working against you - a near impossible situation for you desire outcome.I know of no mortgage insurance company that will issue MI on a "cash out" refinance and so you are limited to 80% -- higher if you refinance the first mortgage only and have the HELOC subordinated. Very unlikely the HELOC will subordinate and there are subordination hits on the first mortgage.5% -- a distant memory. The financial world has finally realized the emperor (Obama) has no clothes. Large increase in rate the past two days. Make you recall the Carter years. Depending on loan size you're likely looking at 5.50% with no point before LLPAs for FICO and LTV start.5.75% on the first is no so bad given the past two days. A 0.25% spread will probably not provide a reasonable repayment of closing costs and 5.5% is a best case rate. HELOC rate is a bit obnoxious (are you certain it's that high?) and the credit card "swap" could work. After all credit card and HELOCs should be reserved for short term financing so it really is a swap but not without risk. Recent government moves may have been politically correct but lacking in financial sense. Banks have about a year before the new dictates go into effect so you might make the "swap" and then see your rate increase retroactive to any existing balance early on before the new rules take effect.FHA would not consider the 1st and 2nd refinance as cash out and there are not LLPAs. Might look at this but pay attention to the APR - 1.75% Up Front MIP plus 0.55% monthly MI. My guess is that you will do best going "nothing" but using any extra money each month to reduce the higher-rate HELOC.

there is a new program that goes up to 125% Loan to value that may help