Should I upgrade to Windows Vista?  

That is a topic of heated debate.

Honestly, a lot of it is based on personal preference, but here are my 2 cents.

Upgrade to Vista only if you:

Want or need some its enhanced multimedia capabilities
Need 64-bit capability in order to utilize large amounts of RAM
Like to tinker with new things and stay on the cutting edge
Want to use an application that requires Windows Vista
There is some feature you heard about in Vista that you just have to have
You know your hardware and software are compatible with Vista

However, be prepared for the following when you upgrade:
Don't even attempt to use Vista without 2GB of RAM unless you like pain - in fact, I'd recommend 4GB - luckily RAM is cheap, assuming your computer can handle 4GB
Most people still have Windows XP - so there are a lot more support resources out there for it (friends, your local fix-it guy, etc) - don't be surprised when you are asking someone for help that their eyes glaze over when you mention you have Vista
Be prepared for little quirks and hardware issues - they still don't have the kinks out yet
Unless your computer is reasonably new and/or you have a lot of memory, expect it to be a little slower running Vista
The user interface is COMPLETELY different - expect to take some time to re-learn the operating system's user interface in Vista

Honestly, unless you know what you are doing, and you are just dying for Vista immediately - wait to get it with a new computer.  Quite often, the cost involved in upgrading your machine to handle Vista and the cost of Vista itself almost costs as much as a new computer running Vista (you can get a Dell desktop with 6GB of RAM running Vista for less than $500).  Thus, for most people, upgrading is just not worth the hassle.

Besides, Windows 7 is right around the corner . . .

Visit http://www.smileyfacepc.com for assistance with Windows XP or Windows Vista.