[brk]

You will find that the greatest accomplishments in the world are often built upon solid foundations.

It's perfectly possible to go from college into a startup (or to skip the college part), but in general you will do better (and contribute more) in a startup when you have some experience in a large company. You may not want to retire from IBM, but it's good to see the good and bad bits about how a large organization is run.

The IBM job may or may not be there in another 5 years. There will always be some startup opportunity available.

[apu]

I would actually argue the opposite: the IBM job (or some equivalent big-company job) will always be there. The startup opportunity at [name your startup here] is only available now.

Big company jobs tend to be alike in many ways (due to their size), whereas startups vary so significantly that it's deceptive to think of all startups as interchangeable.

So yes, there will always be some startup opportunity available, but if you know that there are good people working at this one, or if they're working on interesting things, then I think it's a better option.

[brk]

Companies like IBM tend to be most interested in finding high-ranking college grads to bring in. Additionally many startups appreciate and value someone who has solid experience at a large organization, coupled with a drive to do more.

Doing it the other way around (try a startup, then go to BigCo) is less optimal.

[apu]

As one data point against your statement, from PG's "Hiring is Obsolete":

I asked managers at Yahoo, Google, Amazon, Cisco and Microsoft how they'd feel about two candidates, both 24, with equal ability, one who'd tried to start a startup that tanked, and another who'd spent the two years since college working as a developer at a big company. Every one responded that they'd prefer the guy who'd tried to start his own company.

http://www.paulgraham.com/hiring.html

[brk]

Don't believe the OP was starting a company, he's coming in as an employee. Big difference.

[deathbob]

"The IBM job may or may not be there in another 5 years. There will always be some startup opportunity available."

Another good point, between this and what ken said I think I'm leaning IBM now.