IBM will pound you. Sadly enough, it's not really worth it. They treat their employees like numbers, not people.
You will be fired in a second if they deem your position not worthy to their bottom line or they find a cheaper alternative. Be warned, they are a HUGE company w/ lots of power but they are VERY cutthroat. Do NOT count on being employed w/ them from one day to the next.
Great cutting-edge company to work for, but they lack job security.
Just be ready for ANYTHING, and answer in the most professional and cutthroat manner you can. Don't be a softy to IBM.
Oh, and CHEERS and good luck! I failed miserably in a primary interview w/ them but got a job w/ a better (IMO) company. Give it your best!