If you don’t have hundreds of dollars then you’re pretty much out of luck…but you should take note that should you wish to upgrade once the next version comes out you’ll need a whole lot more since CS2 is currently the earliest version eligible for upgrading and will no longer be upgradable whenever the next CS is released (based on current policy).
Also, if you have a suite you can’t upgrade just InDesign but must upgrade the full suite.
Finally, if you’re going to do it, now’s the best possible time. All upgrades are 20% off. Here’s an Amazon link to the CS5.5 from CS2 Design Premium upgrade: http://amzn.to/kZOsu7
Here’s the Design Standard: http://amzn.to/ir5i7j
If you do have a stand alone InDesign license here’s the upgrade for you: http://amzn.to/p6tI1e
Hope that helps,
You didn'tmention the sort of hardware you have. You'll want to check the system requirements BEFORE spending money to upgrade software on inadequate hardware. Keep in mind, too that those are MINIMUM requirements listed, which means the applicatons will run,but not necessarliy with improved performance.
With the exception of the Intel only, of course. That is carved in stone.