Flat panel monitor/XBOX

I recently purchased a new computer and it came with a new flat panel monitor.
My question is, could I use my old 15" flat panel monitor with my XBOX. Is it
even worth it?

you could yea. but why not just use it with your tv. its probably bigger.

watch out when you using LCD or TFT screens.
Many people dont like using those for games because the refresh rate sometimes isnt as good as CRT monitors. I noticed this with my cousins flat panel. Games like CS tended to lag a little giving a "drunk" feel (much like you move your head...then you feel the image moving).

Plus, as mentioned...the screen is small. If you play any 2 player shooters its not going to be as fun. I played 4 player Perfect Dark on N64 on a 10inch TV before. It was pretty sad. Couldnt see anything. Shoot and hope for the best.