I have some tax information for you to consider before you commit to a move from Canada to the USA. The USA is the only country in the world, that taxes citizens, permanent residents, and green card holders on income regardless where it is earned or where that person lives.
Until recently, this law was not enforced, so alot of former US residents who did not know this was the law, did not file annual tax returns. In 2010, the USA adopted FATCA (foreign account tax compliant act), which will require banks in all countries to report on the accounts of all 'US persons' (citizens, duals, former residents, green card holders) directly to the IRS.
Firstly, what this means, is that if you return to Canada down the road, you need to be aware that you will continue to have to file US tax returns every year, and possibly pay US taxes. There is some tax relief due to a US-Canada tax treaty, but it is difficult to escape from some double taxation. The costs to file USA tax returns are more expensive and complicated than Canadian tax returns.
If you do not become a US citizen, and some day return to Canada, as long as you give up your green-card (and not just throw it in a drawer and forget about it), you may be able to avoid this tax obligation upon your return to Canada, but I am not 100% on this.
Secondly, while you are working in the USA, you are required to report all your 'foreign' accounts (i.e. any bank accounts you still have open in Canada) to the IRS on FBAR forms (foreign bank account forms). Failure to do this can result in high penalties. Since FATCA is coming, the banks will let the IRS know about your Canadian accounts if you don't.
Check out: isaacbrocksociety.ca/