Gayle, I recently got an offer from a major software company, but it's not quite what I was hoping for. How can I negotiate my offer?
~ PV

First of all, you're off to a great start by just trying to negotiate. Most people don't even do that.

Much of the standard negotiation advice applies here:

Having competing offers will give you leverage
Know what you can get an other companies (goes back to the competing offers thing)
Being able to quantify your value to the company - what can you do for them?
Think big picture. Maybe you can't get a salary bump, but perhaps you can get a better signing bonus. Or maybe you can get relocation in cash, instead of the company directly paying for it. Or, perhaps you can get an agreement for an earlier review or opportunity for promotion.

One thing to note with big companies like Microsoft is that they often have "levels" for employees, with a small salary range for anyone at that level. You have some wiggle room within that range, but larger bumps may require jumping up to the next level. You'll need to understand what you need to demonstrate to reach that level, and use examples from your past to demonstrate that you have these qualities.