Applying for SSN and returning back to CANADA

Hi,

Im currently working in canada on work permit, which expires on 26th of July 2005.

I have got a job in US from another employer and got my H1B processed, my employer is asking me to come to US to apply SSN and go back to Canada.

Is it allowed to come there and apply SSN and get back to canada within 2 or 3 days.

Will i have any problem on reentering canada with the same work permit as Im planning to resign my current job only after i get my SSN.

Im in urgent need of info .. kindly help me.

Thanks in advance