The Wall Street Journal recently assessed Obama and McCain's health care plans (October 23, 2008; Personal Journal Section, D1). Depending on your income, health status and what kind of insurance you currently have the plans may have different effects on your insurance situation. The WSJ concluded that Obama's plan would tackle the large (and growing) uninsured population, but both plans could reduce out-of-pocket spending for Americans in the short-term.
How much will each candidates' health insurance programs cost? The Tax Policy Center has suggested both plans will cost between 1.3 (McCain) and 1.6 (Obama) trillion dollars over 10 years; however, the Lewin Group determined McCain's plan would cost almost twice as much as Obama's plan ($2.1 vs. 1.2 trillion).
Both candidates plan to use money from taxes (by rolling back the Bush tax cuts) or other incentives (taxing employer health benefits) to offset the costs of their health care proposals. I encourage you to read the full article if you have a chance.